CM8001 Group 4 http://ossarchive.adm.ntu.edu.sg/2016-17/cm8001-group-4 Dangers of Antibiotics Misuse Tue, 10 Apr 2018 23:46:29 +0000 en-US hourly 1 https://wordpress.org/?v=4.7.5 Unit 9: Molecules and Drugs http://ossarchive.adm.ntu.edu.sg/2016-17/cm8001-group-4/unit-9-molecules-and-drugs/ http://ossarchive.adm.ntu.edu.sg/2016-17/cm8001-group-4/unit-9-molecules-and-drugs/#respond Thu, 05 Apr 2018 06:33:50 +0000 http://ossarchive.adm.ntu.edu.sg/2016-17/cm8001-group-4/?p=303 Questions for CM8001-AE 9 1.In allergy sufferers, histamine causes runny noses, red eyes, and other symptoms. Here is its structural formula.   a. Give the chemical formula for this compound. C5H9N3 b. Circle the amine functional group in histamine. c. Which part (or parts) of the molecule make the compound water-soluble?  Amine group , -NH group and double bond make the… Read more →

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Questions for CM8001-AE 9

1.In allergy sufferers, histamine causes runny noses, red eyes, and other symptoms. Here is its structural formula.  

Image result for histamine structural formula

a. Give the chemical formula for this compound.

C5H9N3

b. Circle the amine functional group in histamine.

c. Which part (or parts) of the molecule make the compound water-soluble? 

Amine group , -NH group and double bond make the compound soluble in water.

2.Antihistamine are widely used drugs for treating symptoms of allergirs caused by reactions to histamine compounds. This class of drug competes with histamine, occupying receptor sites on cells noramlly occupied by histamine. Here is the structure for a particular antihistamine.

a. Give the chemical formula for this compound.

C16H21N3

 

b. What similarities do you see between this structure and that of histamine (shown in the previous question 1) that would allow the antihistamine to compete with histamine?

Histamine and antihistamine are compounds that have opposite effects on the human body. Histamines trigger an allergic response while antihistamines calm it. The human body is able to create both of these chemical messengers on its own, though they can also be introduced into the body from outside sources. Since a histamine and an antihistamine compete for the same receptors, an antihistamine can block the effect of the histamine.

The similarities in the two structures are a two-carbon chain with a nitrogen at the end , and a three-atom sequence of N-C-N. Given the similarities in structure, we might guess that the antihistamine would bind to histamine receptor sites on cells more tightly than histamine itself, thus blocking histamine action. And also, when histamine and antihistamine are both present at the same time, antihistamine cancels the effects of histamine. This is because once antihistamine binds to the receptor site, it blocks the effects of histamine as histamine is unable to bind to the receptor site. No chemical messengers would be produced by histamine.

 

 

3. Consider this statement. ” Drugs can be broadly classed into two groups: those that produce a physiological response in the body and those that inhibit the growth of substances that cause infections.” Into which class does each of these drugs fall? 

a. aspirin

Aspirin is classified as a drug that produces a physiological response in the body. Aspirin binds to COX-1 enzymes that are involve in the production of prostagalandins and prevent the conversion of arachidonic acid to prostagalandin. Prostagladins are messenger molecules that call for swelling, fever, increase pain, inhibit dilation of blood vessels, regulate production of acid and mucus in the stomach and assist kidney functions. Thus, the physiological response of aspirin is the inhibition of prostagladin activity.

b. morphine

Morphine is classified as a drug that produces a physiological response in the body. Morphine binds to opiate receptors in the brain and releases chemicals that binds to the GABA receptor. The binding of these chemicals inhibits the activity of GABA which is to shut down the release of dopamine. As such, Dopamine can be released into the synapatic cleft, allowing it to bind to dopamine receptor on the post-synaptic membrane to signal for pleasure. Thus, the physiological response of morphine is the pleasure that is felt.

c. (Keflex) antibiotic

Keflex is classified as a drug that inhibit the growth of substances that cause infections. Keflex is a bactericidal agent that acts by the inhibition of bacterial cell-wall synthesis. As such, this prevents the growth and development of bacteria in the body. Without bacteria growth and propagation, bacteria cannot initiate a sizable effect on the body to cause an infection.

d. estrogen

Estrogen is classified as a drug that produces a physiological response in the body. It mimics the effects of the natural hormone and is responsible for the development and regulation of the female reproductive system and secondary sex characteristics. Estrogen is used as medication as part of some oral contraceptive, in hormone replacement therapy for postmenopausal, hypogonadal, and transgender women, and in the treatment of certain hormone-sensitive cancers like prostate cancer and breast cancer.

e. amphetamine

Amphetamine is classified as a drug that produces a physiological response in the body. It is a central nervous system stimulant that affects chemicals in the brain and nerves that contribute to hyperactivity and impulse control. It is used to treat attention deficit hyperactivity disorder (ADHD), narcolepsy and obesity.

f. penicillin

Penicillin is classified as a drug that inhibit the growth of substances that cause infections. It is a group of antibiotics which include penicillin G (intravenous use), penicillin V (use by mouth), procaine penicillin, and benzathine penicillin (intramuscular use). It fights bacteria in your body and is used to treat many different types of infections caused by bacteria, such as ear infections. Specific structural requirements are equated to constructing the perfect ‘trap’ for catching targeted bacteria.

 

4. Herbal or alternative medicine are not regulated in the same way as prescription or OTC medicines. In particular, this issues of concern are identification and quantification of the active ingredient, quality control in manufacture, and side effects when the herbal remedy is used in conjunction with another alternative or prescription medicine. 

a. What do you think is the evidence from herbal supplement manufacturers that address these issues?

Some herbal supplements do contain harmful bacteria, pesticides or substantial amount of toxic heavy metals. Manufacturers omit some of the ingredients when listing on the labels. This was investigated by Food and Drug Administration (FDA) of the United States in 1994, as herbal products became more popular then.

Furthermore, manufacturers do mix or substitute the ingredients just to reduce cost or for convenience. This causes complication which such products. Contamination is also prone as plants growing together may cause some form of confusion when identifying them. Crops being mad in such way give rise to integrity issues which are faced by the buyer as they are not sure if they will be able to get the right product or herb.

In much recent 2013, 44 herbal supplements were sampled by researchers from Toronto, and the results shown that more than half contains other ingredients that are not listed on their labels. Majority were contaminated. The research was don using DNA bar coding analysis, where 48% of the supplement contains what was listed on the label.

 

b. Do you know anything about Singapore’s legislation on the topic? 

Chinese Proprietary Medicine (CPM) used in Traditional Chinese medicine (TCM) are medicinal products often associate with herbs. This products are usually in tablets, capsule and liquid forms, and are regulated by the Health Science Authority (HSA). A set of safety and quality compliance regulations must be met before these products can be marketed in Singapore. These sellers of such products have to receive license authorised by HSA in order to sell their products in Singapore.

 

Reference:

Health Science Authority. 2016. Use of Chinese Proprietary Medicines. Retrieved from: http://www.hsa.gov.sg/content/hsa/en/Health_Products_Regulation/Consumer_Information/Consumer_Guides/Complementary_Health_Products/Use_of_Chinese_Proprietary_Medicine.html

 

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Video Content http://ossarchive.adm.ntu.edu.sg/2016-17/cm8001-group-4/video-content/ http://ossarchive.adm.ntu.edu.sg/2016-17/cm8001-group-4/video-content/#respond Wed, 29 Mar 2017 06:45:34 +0000 http://ossarchive.adm.ntu.edu.sg/2016-17/cm8001-group-4/?p=291 Introduction Have you ever wondered: Why antibiotics are not panaceas? Why antibiotics are not as effective? Why are there numerous antibiotics for one purpose? All these are due to antibiotics resistance! To understand antibiotics resistance, we need to first learn more about bacteria! Chemical Concept   What are bacteria? Bacteria are prokaryotes, which consist of a single cell with a… Read more →

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Introduction

Have you ever wondered:

Why antibiotics are not panaceas?

Why antibiotics are not as effective?

Why are there numerous antibiotics for one purpose?

All these are due to antibiotics resistance!

To understand antibiotics resistance, we need to first learn more about bacteria!

Chemical Concept

 

What are bacteria?

Image result for bacteria

Bacteria are prokaryotes, which consist of a single cell with a simple internal structure.

They are only a few micrometers in size.

Image result for bacteria

 

Image result for bacteria

Bacteria generally appear in 3 different shapes- Spherical, Rod and Spiral.

These organisms can be found almost everywhere except for places that have been sterilized thoroughly. Some bacteria are found in extreme condition such as volcanoes, freezing polar regions and also deep underneath the ocean where pressure is high.

 

How Bacteria make us ill? / How bacteria cause illnesses?

When bacteria enters the body, they multiply and crowd body tissues to disrupt normal function kill the body cells and tissues by excreting chemicals that paralyzes the cell. They also can react in the body to produce toxins.

Related image Related image

Image result for bacteria in stomach

 

So how does the body get rid of bacteria?

Our immune system in our body will fight off foreign bacteria that weakens the body but if the infection is too serious, antibiotics is here help!

 

 

 

Antibiotics are medicines to treat infections/diseases caused by bacteria and parasites. Antibiotics can be taken orally, by injection or as creams, ointments or lotions to apply to skin.

Image result for antibiotics as cream  Image result for antibiotics injection Image result for antibiotics

 

The discovery of antibiotics by Sir Alexander Fleming have saved millions of lives since it was first publicly used.

 

 

 

 

 

Gram Positive and Negative Bacteria

 

 

 

Antibiotic Resistance Process

 

 

Implication to Society

 

 

http://robertclaremd.com/wp-content/uploads/2016/02/IMG_1929.jpg

Beware: Misuse of antibiotics May Cause Resistance which May Lead to Death

Image result for curing bacterial infection using natural product

 

 

VIDEO: CHEMICAL CONCEPT 

1st half of video 

1.Bacteria are prokaryotic organisms that are only a few micrometers in size  (BACTERIA PICTURE)

2. Some bacteria are able to enter the body

  • multiply and crowd body tissues to disrupt normal functions
  • kill body cells and tissues by excreting chemicals
  • react in the body to produce toxins.

3. Antibiotics are medicines to treat infections/diseases caused by bacteria

  • target the cell wall of the bacteria and block the process by which bacteria combines molecules together. This causes the pressure in the cell to build up and eventually burst.  (CELL WALL PICTURE)
  • target the ribosomes in the cell of the bacteria. They prevent the ribosomes from producing proteins for the cell. Without proteins, the cell cannot to survive as proteins are the necessity to do work. (RIBOSOME PICTURE)
  •                        
  • target the DNA replication mechanism of the bacteria. (DNA REPLICATION PICTURE)

BUT

2nd half of video

4. Bacteria can become resistant to antibiotics

  • As a consequence of accumulated mutations in bacteria, some bacteria would already have antibiotic drug resistance (PICTURE 1/4)
  • When bacteria  is exposed to a antibiotic, those bacteria without resistance would be killed while those with resistance would continue to propagate (PICTURE 2/4)
  • As such, it is expected that the new colonies of bacteria produced would all have antibiotic resistance (PICTURE 3/4)
  • These new colonies of bacteria are then able to pass on their genes either through lateral transfer to other bacteria or vertical transfer to their offspring. (PICTURE 4/4)

5. Thus, development of antibiotic resistance becomes a problem as current antibiotics medicine loses its effectiveness as an increasing rate.  We will look at the implication of this in the next video.

 

VIDEO: IMPLICATIONS TO SOCIETY

Misuse of antibiotics continues to promote development of antibiotic resistance in bacteria.

 

  1. Main Causal factors
    • Growing reliance on feeding antibiotics to livestock for:
    • growth promotion (Genetically modified vs Farm) 
    • weight gain             
    • and to treat, control and prevent disease Image result for vaccinating chickens
      • Path of bacteria from animals to humans
      • Many cycles of food consumption from different sources : resistance sharing between bacteria leads to the formation of a super bacteria which is resistant to many drugs.  Difficult to treat once it infects the patient as many antibiotics will not work.
    • Clinical overuse of antibiotics
  2.  Effects
    • Drive up drug and hospital cost:
      • As antibiotic resistance spreads, more and more commonly used antibiotics must be retired. More funds must be funneled into development of new antibiotics, driving up the cost of antibiotics that are effective in treatment
      • $20 billion in health care costs each year in the U.S.  $35 billion loss in productivity
    • Detrimental effects on human health:
      • Ridding patients of infection requires longer treatment
      • Greater disability and death due to absence of effective treatment
        • Image result for diarrhea Image result for disabilityImage result for dead
        • e.g fatal diarrhea in children: children given antibiotics for routine upper respiratory infections are more susceptible to aggressive antibiotic-resistant strains of the bacteria clostridium difficile, commonly known as C-diff. Responsible for 250,000 infections in hospitalized patients and 14,000 deaths every year among children and adults
        • Image result for death due to ineffective antibiotic treatment
      • Killing  good bacteria with antibiotics
      • Image result for killing good bacteriaImage result for good bacteria yakult
        • May be contributing to rises in chronic health conditions such as obesity, asthma and cancer
        • Image result for obesity by antibiotics Image result for asthma by antibiotics
        • wipe out many good gut bacteria while leaving those immune to antibiotics to flourish.
  3. Things professionals can do
    • Prescribe antibiotics only for infections they believe to be caused by bacteria.
    • Image result for doctor antibiotic over prescription
    • Remind patients of the direction for proper use:
      • Complete the full course of the drug.
      • Do not skip doses.
      • Do not save antibiotics.
      • Do not take antibiotics prescribed for someone else.
      • Talk with your health care professional when in doubt.
      • Image result for doctor advice
      • Image result for not completing antibiotic
  4.  Things we can do
    • Use antibiotics only as prescribed by your doctor.
      • Take the appropriate daily dosage and complete the entire course of treatment.
    • Don’t pressure your doctor to give you an antibiotic prescription.
    • (crop out picture, title and point #4)
      • Ask your doctor for advice on how to treat symptoms.
      • Image result for dangers of self medication
    • Practice good hygiene.
      • Wash your hands regularly with soap and water, especially after using the toilet, before eating, before preparing food and after handling fresh meat.
      • Image result for hand washing
      • Wash fruits and vegetables thoroughly, and keep kitchen work surfaces clean.
    • Make sure you or your children receive recommended vaccinations.
    • Image result for children vaccination against bacteria
      • Some recommended vaccines protect against bacterial infections, such as diphtheria and whooping cough (pertussis).

 

 

 

 

 

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Unit 8: The World of Polymers and Plastics http://ossarchive.adm.ntu.edu.sg/2016-17/cm8001-group-4/unit-8-the-world-of-polymers-and-plastics/ http://ossarchive.adm.ntu.edu.sg/2016-17/cm8001-group-4/unit-8-the-world-of-polymers-and-plastics/#respond Wed, 22 Mar 2017 08:30:19 +0000 http://ossarchive.adm.ntu.edu.sg/2016-17/cm8001-group-4/?p=239 Questions for CM8001-AE 7 1. When Styrofoam packing peanuts are immersed in acetone (the primary component in some nail-polish removers), they dissolve. If the acetone is allowed to evaporate, a solid remains. The solid still consists of Styrofoam, but now it is solid and much denser. Explain. Hint: Remember that Styrofoam is made with foaming agents. When Styrofoam is immersed in… Read more →

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Questions for CM8001-AE 7

1. When Styrofoam packing peanuts are immersed in acetone (the primary component in some nail-polish removers), they dissolve. If the acetone is allowed to evaporate, a solid remains. The solid still consists of Styrofoam, but now it is solid and much denser. Explain. Hint: Remember that Styrofoam is made with foaming agents.

When Styrofoam is immersed in acetone, it dissolves into liquid form, allowing gaseous particles in the foaming agent to escape. Evaporation of the acetone from the solution then reverts the Styrofoam back into solid form. The solid Styrofoam then collapses on itself and becomes denser than before due to the release of gaseous particles.

The release of gaseous particles results in the Styrofoam becoming denser due to closer packing of polystyrene molecules. In the presence of a foaming agent, the gaseous particles disrupts the close packing of polystyrene, thus reducing the density. After the gas molecules are released, the polystyrene molecules are better able to adopt a crystalline structure, resulting in higher density.

2. Consider Spectra, Allied- Signal Corporation’s HDPE fiber, used as liners for surgical gloves. Although the Spectra liner has a very high resistance to being cut, the polymer allows a surgeon to maintain a delicate sense of touch. The interesting thing is that Spectra is linear HDPE, which is usually associated with being rigid and not very flexible. 

a. Suggest a reason why branched LDPE cannot be used in this application.

Branched LDPE have weaker inter-molecular forces of attraction, thus less energy are required to break the forces holding LDPE molecules together. This results in the lower tensile strength of LDPE compared to HDPE.

b. Offer a molecular level reason for why linear HDPE is successful in this application.

First, linear HDPE have straight polyethene molecules that are aligned in the same orientation. This arrangement increases the inter-molecular forces of attraction between molecules, allowing for high tensile strength.

Second, linear HDPE allows the surgical gloves to be made thin while still having high tensile strength. This thin layer allows for greater precision movement that is needed in surgery.

Third, linear HDPE  allows for flexible movement, enabling ease of movement of the fingers during surgery.

3. When you try to stretch a piece of plastic bag, the length of the piece of plastic being pulled increases dramatically and the thickness decreases. Does the same thing happen when you pull on a piece of paper? Why or why not? Explain on a molecular level.

When the piece of plastic is stretched, the strip narrows and “necks down.” The molecules become aligned parallel to each other and in the direction of the pull. Furthermore, this alteration of the three-dimensional structure is not reversible and if the pulling continues, the length increases and thickness decreases, causing the plastic to break eventually. When the same pulling force is applied to a piece of paper, the paper tears rather than it stretching to any significant extent. The cellulose molecules in paper are held far more rigidly in place and are not free to become aligned, hence it is unable to stretch like how plastic does.

4. A Teflon ear bone, a Fallopian tube, or heart valve? A Gore-Tex implant for the face or to repair a hernia? Some polymers are bio-compatible and now used to replace or repair body parts.

a. List four properties that would be desirable for polymers used within the human body.

  1. Non-Toxic to the human body.
  2. Lack of chemical reaction with body fluids.
  3. Easy to be implanted.
  4. Stable over time of intended usage.

b. Other polymers may be used outside your body, but in close contact with it. For example, no surgeon is needed for you to use your contact lenses- you insert, remove, clean and restore them yourself. From which polymers are contact lenses made? What properties are desirable in these materials? Either a call to an optometrist or a search on the Web may provide some answers.

There are many different types of contact lenses and each of them uses different types of polymer. The first polymer contact lenses became commonly available in the early 1960s and were made from a polymer called poly(methylmethacrylate) (PMMA). Lenses made of PMMA are called hard lenses. PMMA lenses are hard, rigid and not very comfortable. The first soft contact lenses were introduced in 1971. These were made from a polymer called polyacrylamide. This polymer is different from PMMA because it contains nitrogen atoms in its structure (PMMA does not contain nitrogen). Polyacrylamide is similar to the polymers used to make acrylic fibers for fabrics. In 1979, the first rigid gas-permeable lenses (also known as RGPs) became available. These lenses are made from a combination of PMMA, silicones and fluoropolymers. This combination allows oxygen to pass directly through the lens to the eye, which makes the lens more comfortable for the wearer.

The properties of an ideal polymer for contact lenses include:

● Transparent ● Some flexibility ● Low density ● Tough ● Unreactive to chemicals on the eye surface ● Easy to manufacture ● Made from a raw material that is available in abundance ● Easy to mould ● Refractive index suitable for bending light rays ● Hydrophilic (‘water-loving’) ● Lets oxygen gas pass through to the eye surface ● Produces lenses that are easy to insert, remove, clean and store.

c. What is the difference in the material used in ”hard” and ”soft”contact lenses? How do the differences in properties affect the ease of wearing of contact lenses? 

PMMA lenses are hard, rigid and not very comfortable; it sometimes takes users many weeks to get used to them. The lenses do not allow oxygen to pass directly to the cornea, which can be damaging to the eye. Users have to put a wetting solution in their eyes before putting the lenses in. Hard lenses are not very popular anymore, even though they give good clarity of vision and are very durable – they can last for years. The first soft contact lenses were introduced in 1971. These were made from a polymer called polyacrylamide. This polymer is different from PMMA because it contains nitrogen atoms in its structure (PMMA does not contain nitrogen). Polyacrylamide is similar to the polymers used to make acrylic fibres for fabrics. When the polyacrylamide chains are cross-linked, the material absorbs water. Substances such as this are called hydrophilic (‘water-loving’). This property makes polyacrylamide a useful material for producing contact lenses. Between 38% and 79% of a soft contact lens is water. This water keeps the lens soft and flexible. However, the high water content also makes the lens more fragile and reduces clarity of vision. Soft lenses are cheaper than hard lenses and this has added to their popularity. In fact, some soft lenses can be used for one day and then discarded.

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Unit 6: Neutralizing the Threat of Acid Rain http://ossarchive.adm.ntu.edu.sg/2016-17/cm8001-group-4/unit-6-neutralizing-the-threat-of-acid-rain/ http://ossarchive.adm.ntu.edu.sg/2016-17/cm8001-group-4/unit-6-neutralizing-the-threat-of-acid-rain/#respond Wed, 15 Mar 2017 09:06:28 +0000 http://ossarchive.adm.ntu.edu.sg/2016-17/cm8001-group-4/?p=183 Questions for CM8001-AE 5 1.Mammoth Cave National Park in Kentucky is in close proximity to the coal-fired electric utility plants in the Ohio Valley. Noting this, this National Parks Conservation Association (NPCA) reported that this national park had the poorest visibility of any in the country. a. What is the connection between coal-fired plants and poor visibility? b. The NPCA… Read more →

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Questions for CM8001-AE 5

1.Mammoth Cave National Park in Kentucky is in close proximity to the coal-fired electric utility plants in the Ohio Valley. Noting this, this National Parks Conservation Association (NPCA) reported that this national park had the poorest visibility of any in the country.

a. What is the connection between coal-fired plants and poor visibility?

b. The NPCA reported ” the average rainfall in Mammoth Cave National Park is 10 times more acidic than natural.” From this information and that in your text, estimate the pH of rainfall in the park.

(A) Coal-fired plants release sulfur dioxide, resulting in sulfate particles forming in the air. Sulfates are the largest contributor to haze in the eastern U.S. due to the region’s large number of coal-fired power plants. Furthermore, sulfate particles grow rapidly to a size that is very efficient at scattering light in humid environments. This worsens the problem in the east and hence, sulfates are responsible for 60 to 85 percent of the poor visibility in eastern parks.

(B) Normally, clean rain has a pH value of between 5.0 and 5.5, which is slightly acidic. However, when rain combines with sulfur dioxide or nitrogen oxides (produced from coal-fired plants in this context), the rain becomes much more acidic. With the rainfall in the park being 10 times more acidic than natural, the estimated pH of the rainfall would be between 4.0 to 4.5 which is typical of acid rain.

2. Here are examples of  what an individual might do to reduce acid rain. For each, explain connection to producing acid rain.

a. Hang your laundry to dry it.

b. Walk, bike, or take public transportation to work.

c. Avoid running dishwashers and washing machines with small loads.

d. Add additional insulation on hot water heater and pipes.

e. Buy locally grown produce and locally produced food.

 

(A) When you hang your own laundry, we do not need to use the dryer. Hence, we save electricity which in turns cut down on energy usage. Power plants in Singapore can then cut down on the burning of coal to generate electricity, causing lesser sulfur dioxide to be released into the air.

(B) By walking, taking public transportation or using a bike to get to work, it reduces the amount of car usage.  As there are lesser car usage, it leads to lesser NO emissions and thus contributing less to the acidity of the rain.

(C) Similarly to part (A), by washing the dishes manually, it eliminates the need to use machines which requires energy to work. Hence, energy consumption is reduced and power plants do not need to burn as much coal to supply the required energy. As a result, lesser coals are burned and lesser sulfur dioxide is released into the air.

(D) By insulating hot water heater and pipes, it reduces energy consumption as Insulated pipes reduces heat loss and can raise water temperature 2°F–4°F hotter than non-insulated pipes. As a result, water is heated up faster and lesser energy is required to do the same task. As mentioned earlier in part (A) and (C), power plants do not need to burn as much coal to supply the required energy. As a result, lesser coals are burned and lesser sulfur dioxide is released into the air.

(E) Tremendous amount of fuel is used to transport foods long distances and combustion of fuels releases carbon dioxide, sulfur dioxide, particulate matter and other pollutants into the atmosphere, causing acid rain. Hence, by buying locally grown food, lesser fuel is used to transport food from overseas, resulting in a reduction in NO emission, thus contributing less to the acidity of the rain.

 

3.

a. Give names and chemical formulas for five acids and five bases.

Acids

  1. Hydrochloric acid (HCl)
  2. Sulfuric acid (H2SO4)
  3. Hydrobromic acid (HBr)
  4. Nitric acid (HNO3)
  5. Phosphoric acid (H3PO4)

Bases

  1. Sodium hydroxide (NaOH)
  2. Calcium hydroxide (Ca(OH)2)
  3. Potassium hydroxide (KOH)
  4. Ammonium hydroxide (NH4OH)
  5. Magnesium hydroxide (Mg(OH)2)

b. Name three observable properties generally associated with acids and bases.

Acids are typically corrosive and produces carbon dioxide when reacted with metals. It tastes sour and turns blue litmus paper red, due to the acidic pH.

Bases are usually soapy and caustic to skin. It turns red litmus paper blue due to the high pH(basic) and tastes bitter.

 

4. The concerns of acid rain vary across the globe. Many countries in North America and Europe have websites dealing with acid rain. Either search to locate one (”Canada, acid rain”) or use these links to websites in Canada, the UK, or Europe. What are the issues in Singapore? Does the acid deposition originate outside or inside the Singapore’s borders?

URL: 

http://www.ec,gc,ca/

http://www.ukawmn.ucl.ac.uk/

http://www.grida.no/

http://www.nea.com.sg /

 

According to the NUS study, Acid rain in Singapore could force native species into extinction. Acid rain has caused the pH in rivers and ponds in Singapore to reduce to 4.4-4.7 pH. Creatures living in Singapore are currently under stressed and  may eventually not be able to cope with the environment and succumb to death. The increase in acidity is mainly caused by the expansion of industry plants  which has led to the rise of sulfur dioxide emission, driving the increase in acid rain.

Both sides of the border play a role in acid deposition in Singapore. Industrial plants, power plants and burning of fossil fuels in Singapore will result in acid deposition. On the other hand, the  recent haze issues caused by our neighboring countries has also contributed to the acid deposition. Aerosols found in haze adds to the formation of acid rain which eventually decreases the pH of water found in rivers and ponds in Singapore.

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Unit 5: Water for life http://ossarchive.adm.ntu.edu.sg/2016-17/cm8001-group-4/unit-5-water-for-life/ http://ossarchive.adm.ntu.edu.sg/2016-17/cm8001-group-4/unit-5-water-for-life/#respond Wed, 22 Feb 2017 09:34:04 +0000 http://ossarchive.adm.ntu.edu.sg/2016-17/cm8001-group-4/?p=112 Questions for CM8001-AE 5 1.How can you purify your water when you are hiking? Name two or three possibilities. Compare these methods in terms of cost and effectiveness. Are any of these methods similar to those used to purify municipal water supplies? Explain. During a hike, a simple method to purify water would to be boil it. The process of… Read more →

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Questions for CM8001-AE 5

1.How can you purify your water when you are hiking? Name two or three possibilities. Compare these methods in terms of cost and effectiveness. Are any of these methods similar to those used to purify municipal water supplies? Explain.

During a hike, a simple method to purify water would to be boil it. The process of boiling destroys many of the harmful microbes present in water, making it safer for consumption. However, boiling of water does not remove chemical contamination within water and requires time to set-up.

Another method of water purification is to use chemical purifiers such as iodine. Iodine purifies water by killing bacteria in water, rendering it bacteriologically safe for consumption. Compared to the boiling of water, chemical purifiers are easy to use by simply being added to water. However, iodine should not be a long term solution for water purification as high concentration of iodine intake is toxic. Moreover, iodine does not add a good taste to water. In recent times, a safer form of purifying water was discovered in the form of ‘aquatabs’. These tablets contain tetraglycine hydroperiodide that kills bacteria while also reducing radioactive iodine within the human body.

A third method of purifying water is to use a filtration device. This method does not require the use of any chemicals. Although it does not remove as much microorganism, a good filtration system can be reused many times to generate relatively clean water for consumption. Recent technological advancement has also lead to the invention of ‘Lifestraws’. This filtration device not only removes 99.99% of waterborne bacteria but is also chemical free,portable and easy to use.

Municipal water supply purification relies on a combination of purifying techniques which includes some similar to the ones listed above. For example, chemicals such as fluorine and chlorine are used extensively in purifying tap water. The use of iodine closely relates to this method of purification. Also, similar filtration systems are used in municipal water. Towns and cities are known to filter water through large filtration systems to remove unwanted contaminants. The concept of a small filtration device closely relates to this by also filtering out unwanted substances.  From the concepts listed above, boiling would be the one that is not commonly used in municipal water supply purification. Over the years, towns and cities have developed a multi-stepped process of water purification consisting of coagulation,sedimentation,filtration and disinfection. These processes have been able to supply high purity tap water without implementing a boiling stage.

2.Explain why desalination techniques, despite proven technological effectiveness, are not used more widely to produce potable drinking water.

There are two common desalination techniques, distillation and reverse osmosis. They are used to remove salts and other impurities present in sea water and also unfiltered water with the use of energy. This use of energy could be the reason why these techniques are not widely used to produce drinking water. However, if there were to be a cheaper alternative, I believe that the latter would be utilized to produce clean drinking water for the masses.

3.Water quality in a chemical engineering building on campus was continuously monitored because testing indicated water from drinking fountains in the building had dissolved lead levels above those established by NEA.

a. What is the likely major source of the lead in the drinking water?

Lead can enter drinking water through corrosion of plumbing materials, especially where the water has high acidity or low mineral content that corrodes pipes and fixtures. This would probably be the major source of lead in the drinking water as it has the largest contact with the water supplied around the building. It is usually more serious with aging buildings because these buildings are more likely to have lead pipes, fixtures and solder. However, new buildings are also at risk because legally “lead-free” plumbing may contain up to eight percent lead.

The most common problem is with brass or chrome-plated brass faucets and fixtures with lead solder, from which significant amounts of lead can enter into the water, especially hot water. Corrosion is the dissolving or wearing away of metal caused by a chemical reaction between water and plumbing of the building. A number of factors are involved in the extent to which lead enters the water including the chemistry of the water (acidity and alkalinity), the amount of lead it comes into contact with, how long the water stays in the plumbing materials and the presence of protective scales or coatings inside the plumbing materials.

b. Do the research activities carried out in this chemistry building account for the elevated lead levels found in the drinking water? Explain.

Yes, research activities carried out in this chemistry building accounts for the elevated lead levels found in the drinking water.

There are proper chemical waste disposal containers placed in fume-hoods, mainly aqueous, chlorinated or non-chlorinated organic waste. These waste will be collected and disposed by special ways through transport to another facility, and never to the sink. Solid waste are transferred into an empty glove, tied up and thrown into the waste bin.

Laboratory manuals and Laboratory technicians do remind students to dispose waste into the respective containers. Furthermore, every student is required to complete and score with a high percentage score for a lab quiz at the start of each semester.

Upon leaving the laboratory to the washroom, students are required to remove gloves and hang their lab coats outside of the washroom, this ensures that student does not carry any unwanted chemical substance that might contaminate the water, even at very low concentration. Water fountains are not located in the laboratory, thus in order to use the water fountain, one has to leave the lab and by doing so, removes his/her gloves (preventing contamination).

These are some measures that chemistry department took to prevent lead from contaminating the potable water supply.

4. Some vitamins are water-soluble, whereas others are fat soluble. Would you expect either or both to be polar compounds. Explain.

The expression “Like Dissolves Like” will determine if the water-soluble or fat soluble vitamins are polar or nonpolar.

Water soluble vitamins are vitamins that are able to dissolves in water. Since the water soluble vitamins possess atoms to attract and to interact with the water molecules through hydrogen bonding, this shows that the vitamins is polar. Examples of water soluble vitamins are Vitamin B Vitamin C.

On the other hand, Fat soluble vitamins are vitamins that are able to interact with fatty solvent. Fat soluble vitamins contains more hydrocarbons (C and H atoms) than polar atom. Although it may contain polar atoms, the non-polar characteristic still outweighs the polar portion. This allows the fat soluble vitamins to interact with the non-polar chains in fatty solvent. Examples of fat soluble vitamins are Vitamin A, Vitamin D, Vitamin E and Vitamin K.

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Unit 3: Global Climate Change http://ossarchive.adm.ntu.edu.sg/2016-17/cm8001-group-4/unit-3-global-climate-change/ http://ossarchive.adm.ntu.edu.sg/2016-17/cm8001-group-4/unit-3-global-climate-change/#respond Wed, 15 Feb 2017 12:35:29 +0000 http://ossarchive.adm.ntu.edu.sg/2016-17/cm8001-group-4/?p=41 Questions for CM8001-AE 4   1. Understanding Earth’s energy balance is essential to understanding the issue of global warming. For example, the solar energy striking Earth’s surface averages 168 watts per square meter (W/m^2), but the energy leaving Earth’s surface averages 390 W/m^2). Why isn’t Earth cooling rapidly?   According to Earth’s Radiation/Energy Budget, there are other factors to consider… Read more →

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Questions for CM8001-AE 4

 

1. Understanding Earth’s energy balance is essential to understanding the issue of global warming. For example, the solar energy striking Earth’s surface averages 168 watts per square meter (W/m^2), but the energy leaving Earth’s surface averages 390 W/m^2). Why isn’t Earth cooling rapidly?

 

According to Earth’s Radiation/Energy Budget, there are other factors to consider other than the energy from solar. “Back radiation” comes from the atmosphere and clouds provides 333 W/m^2 which is high enough to heat the earth surface and to keep the earth warm and hot. However, Earth’s Radiation/Energy Budget does not include anthropogenic emission which plays a big role in the warming of the earth surface. With the addition of all these activities caused by humans, the earth can never cool down.

 

2. Decide and explain whether the statement is correct or incorrect. Explain.

 

This statement is incorrect. We start off with with some definitions. Winter is defined as the coldest season of the year, in the northern hemisphere from December to February and in the southern hemisphere from June to August. Global warming refers to a gradual increase in the overall temperature of the earth’s atmosphere generally attributed to the greenhouse effect caused by increased levels of carbon dioxide, CFCs, and other pollutants. The general misconception about this question is the difference between weather and climate. The author is basically saying that just because it snowed at some places and the temperature  decreased, the planet must not be warming. We experience winter as a result of Earth’s tilted axis as it revolves around the sun and so it will occur with or without global warming. Even though the planet is getting warmer, cold weather still happens in winter or at very high elevations or high latitudes year-round.  Federal agencies, universities, and research centers around the world have all concluded that Earth is warming, hence it is wrong to assume that just because there is winter, it will help to lower the temperature of the earth and help with the situation of global warming. In conclusion, winter does not help in reducing global warming and checking Earth’s average surface temperature annually will help to determine the severity of global warming.

 

3. One of the first radar devices developed during World War II used microwave radiation of a specific wave range that triggers the rotation of water molecules. Why was the design not successful?

 

Firstly, the absorption of microwave radiation by water in the atmosphere might interfere with the detection of intended objects, hence the accuracy of the radar might diminish and information provided could not be depended on when attacks such as air strikes had to be conducted. Secondly, the triggering of rotation of water molecules with that specific wave range will also increase the temperature (average kinetic energy) of water when exposed to the radiation, leading to the accidental discovery of the microwave oven during the war.

 

4. Now that you have studies air quality (Unit 1), stratospheric ozone depletion (Unit 2), and global warming (Unit 3), which do you believe poses the most serious problem for you in the short run (pick one and explain)? In the long run (Pick one and explain why)?

 

In my opinion, all poses serious problems in the short and long run to a certain extent. However, I strongly believe that air quality is the most damaging to human health in the short run. Breathing is crucial for the human bodies to function and it is vital not only for human beings, but for all living things as well. The air we breathe in goes in directly into our blood and runs through the entire body. Not breathing for a few minutes could cause damaging outcome or even death. As such, having bad air quality in the environment will not only affect one area but the whole body.

On the other hand, I feel that ozone depletion would be the least harmful. When unwanted ultraviolet pierce through our atmosphere, health problems such as cancers would develop in our bodies. Although it will eventually cause death, it is still a very slow process as all the health problems are mostly carcinogenic.

 

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Unit 4: Energy and Combustion http://ossarchive.adm.ntu.edu.sg/2016-17/cm8001-group-4/unit-4-energy-and-combustion/ http://ossarchive.adm.ntu.edu.sg/2016-17/cm8001-group-4/unit-4-energy-and-combustion/#respond Thu, 09 Feb 2017 08:52:17 +0000 http://ossarchive.adm.ntu.edu.sg/2016-17/cm8001-group-4/?p=29 Questions for CM8001-AE 3   1.From personal experience, state whether these processes are endothermic or exothermic. Give a reason for each. a. A charcoal briquette burns Hot sensation felt by the skin suggest that the burning of charcoal produces heat, thus an exothermic process. b. Water evaporates from your skin. Skin feels cold. Heat energy from the human is used… Read more →

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Questions for CM8001-AE 3

 

1.From personal experience, state whether these processes are endothermic or exothermic. Give a reason for each.

a. A charcoal briquette burns

Hot sensation felt by the skin suggest that the burning of charcoal produces heat, thus an exothermic process.

b. Water evaporates from your skin.

Skin feels cold. Heat energy from the human is used by the water to break the inter-molecular forces of attraction between water molecules to form water vapor. Liquid phase to gaseous phase. Hence, an exothermic process.

c. Ice melts.

Similar to part B, the feeling is the same. However, the change of physical states are different. Ice melts, takes in energy to break the inter-molecular forces of attraction. Solid phase to liquid phase. Hence, an exothermic process.

 

2. Chemical explosions are very exothermic reactions. Describe the relative bond strengths in the reactants and products that would make for a good explosion.

An exothermic reaction produces heat. The larger the explosion the more heat is given out. This can be explained by calculating the Enthalpy of a reaction, ΔH = – [ (sum of product bond energies) – (sum of reactant bond energies)]

For a reaction to be exothermic, reactants must have higher energy than products in terms of bond energies. The higher the reactants energy and the lower the products energy, the bigger the difference and this difference will be the result of the amount of energy(heat) given off. As a result, in order to produce a BIG explosion, the amount of energy given off must be huge.

3. How might you explain the difference between temperature and heat to a friend? Use some practical, everyday examples?

By taking two objects of the same temperature and place them into contact of each other, there will not be overall transfer of energy as the average energies of the particles in each object are the same. However, if one of the object has a different temperature, the object that has a higher temperature will transfer its energy to the colder object until both reach the same temperature. This shows that heat is energy and will increase or decrease the temperature. Heat is the total energy of molecular motion in a substance and is dependent on the speed and the number of particles. On the other hand, temperature is not energy but a measure of it. Temperature is a measure of average energy of molecular motion (rotation or vibration) in a substance. Temperature does not depend on size or type of object.

 

4. A premium gasoline available at most stations has an octane rating of 98. What does that tell you about:

a. the knocking characteristics of this gasoline?

 An octane rating of 98 suggests that this gasoline has a knocking characteristic of 98% isooctane and 2% heptane. Its ability to burn smoothly without knocking is lower but close to isooctane and  greatly higher than heptane. 

b. whether the fuel contains oxygenates?

Oxygenated fuels tend to have octane rating above 100 as these gasoline are able to burn more smoothly without knocking compared to isooctane. An octane rating of 98 suggests that this gasoline is not oxygenated as its ability to burn smoothly without knocking is below that of isooctane which has an octane rating of 100. The oxygenation of fuels generally increases the octane number above 100 as oxygenated fuels requires a higher activation energy to initiate combustion. As such, the occurrence of uncontrolled ignition becomes less unlikely. Therefore, since isooctane is a non-oxygenated fuel, a fuel with even lower octane rating would not be oxygenated as well. 

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HELLO http://ossarchive.adm.ntu.edu.sg/2016-17/cm8001-group-4/hello/ http://ossarchive.adm.ntu.edu.sg/2016-17/cm8001-group-4/hello/#respond Wed, 25 Jan 2017 07:54:18 +0000 http://ossarchive.adm.ntu.edu.sg/2016-17/cm8001-group-4/?p=17 waterrr  Read more →

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Cars and Pollution http://ossarchive.adm.ntu.edu.sg/2016-17/cm8001-group-4/cars-and-pollution/ http://ossarchive.adm.ntu.edu.sg/2016-17/cm8001-group-4/cars-and-pollution/#respond Wed, 25 Jan 2017 07:54:15 +0000 http://ossarchive.adm.ntu.edu.sg/2016-17/cm8001-group-4/?p=12 Particulate matter. These particles of soot and metals give smog its murky color. Fine particles — less than one-tenth the diameter of a human hair — pose the most serious threat to human health, as they can penetrate deep into lungs. PM is a direct (primary) pollution and a secondary pollution from hydrocarbons, nitrogen oxides, and sulfer dioxides. – I… Read more →

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Particulate matter.

These particles of soot and metals give smog its murky color. Fine particles — less than one-tenth the diameter of a human hair — pose the most serious threat to human health, as they can penetrate deep into lungs. PM is a direct (primary) pollution and a secondary pollution from hydrocarbons, nitrogen oxides, and sulfer dioxides.

– I just got to know chemistry on a whole new level. Interesting.

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Learning Points http://ossarchive.adm.ntu.edu.sg/2016-17/cm8001-group-4/what-we-learnt/ http://ossarchive.adm.ntu.edu.sg/2016-17/cm8001-group-4/what-we-learnt/#respond Wed, 25 Jan 2017 07:54:12 +0000 http://ossarchive.adm.ntu.edu.sg/2016-17/cm8001-group-4/?p=6 Today we learn about the air we breathe in and air pollution. We were taught the different types of air pollutant and how they were formed. . Read more →

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Today we learn about the air we breathe in and air pollution. We were taught the different types of air pollutant and how they were formed.

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