CM8001 Group 6 http://ossarchive.adm.ntu.edu.sg/2016-17/cm8001-group-6 The Impact of Chemistry on Society Fri, 06 Apr 2018 04:48:52 +0000 en-US hourly 1 https://wordpress.org/?v=4.7.5 CM8001 Application Exercise (5th April) http://ossarchive.adm.ntu.edu.sg/2016-17/cm8001-group-6/cm8001-application-exercise-5th-april/ http://ossarchive.adm.ntu.edu.sg/2016-17/cm8001-group-6/cm8001-application-exercise-5th-april/#respond Thu, 05 Apr 2018 07:39:28 +0000 http://ossarchive.adm.ntu.edu.sg/2016-17/cm8001-group-6/?p=191 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.

Ans: C5H9N3

b. Circle the amine functional groups in histamine.

Ans: 

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

Ans: 

 

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

a. Give the chemical formula for this compound.

Ans: C16H21N3

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

Ans:

The two-carbon chain with a nitrogen at the end (marked in red) and a three-atom sequence of N-C-N (marked in blue), as well as the spatial placement of these pieces are similar. The flat 5-ring of histamine is also relatively similar to the flat 6-ring of the antihistamine.

The antihistamine would bind to the histamine receptor sites on cells more tightly than histamine itself, thus block the histamine actions.

 

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?

Antibiotic (Keflex) & Penicillin inhibit the growth of substance that cause infection. Aspirin, Morphine, Estrogen and Amphetamine produce a physiological response in the body.

 

4.Herbal or alternative medicines are not regulated in the same way as prescription or OTC medicines. In particular, the 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?

Ans: Products such as herbs can sometimes be tainted with pesticides, germs, or toxic heavy metals. Ingredients and its amount listed on labels are sometimes misrepresented — some supplements do not contain what’s listed on the label, contain more or less than the amount, or are not listed on the label at all. In 2013, researchers in Toronto published a report in which they sampled and analyzed 44 herbal supplements and found that 48% of the supplements contained any of the herb listed on the label. More than half of the supplements contained something that wasn’t on the label.

Some herbal suppliers (those who grow, harvest, or sell the crops) may practice unethical behaviours, by mixing or even substituting their crops with less expensive or more readily available plants. Accidental contamination is also an issue, when one plant grows in with others, as well as cases of mistaken identity (when one plant looks like another). These problems can make it harder for a company to be sure that what they thought they were buying to make supplements is actually the herb they wanted.

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

Ans: Health supplements are currently not subjected to premarket approvals or licensing for their importation, manufacture and sales in Singapore. However, dealers have the obligation to make sure that such products are safe to consume and they conform to quality standards and safety.

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CM8001 Application Exercise (22nd March) http://ossarchive.adm.ntu.edu.sg/2016-17/cm8001-group-6/cm8001-application-exercise-22nd-march/ http://ossarchive.adm.ntu.edu.sg/2016-17/cm8001-group-6/cm8001-application-exercise-22nd-march/#respond Thu, 23 Mar 2017 09:28:05 +0000 http://ossarchive.adm.ntu.edu.sg/2016-17/cm8001-group-6/?p=110 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.)

Answer: Acetone dissolves the polymer which enables the gas of the foaming agent to escape. Since the gas has been removed, the polymer collapses on itself and become more dense.

 

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.

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

Answer: a) LDPE cannot be used in this application due to the insufficient strength it possesses.

Answer: b) The molecules of HDPE must be arranged in a way that will give the required strength. In order to have the sufficient flexibility, a thin liner of HDPE is used.

 

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.

Answer: The paper tears rather than stretching to any significant extent when the same pulling force is applied. The cellulose molecules in paper are being held more rigidly in place as compared to the cellulose molecules in plastic bag, and are not free to become aligned.

 

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

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

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 store 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.

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

 

Ans: a) The four properties are: (1) stable over time of intended use, (2) non-toxic, (3) low cost and (4) the ease of implantation.

Ans: b) Several different types of contact lenses are on the market and each uses a different type of polymer. These include Polymethyl methacrylate (PMMA), Silicone-acrylate materials, newer rigid gas permeable (RGP) polymers, Polymacon.

Desirable properties include being nontoxic, permeable to oxygen, comfortable to wear, and inexpensive. Also desirable is the ability to conform to the shape of the eye and to be easily cleaned (if not disposable).

Ans: c) Hard contact lenses are typically made of PMMA whereas soft contact lenses are made of silicone, which is flexible and allows oxygen to reach the eye. The soft lenses tend to be more comfortable as compared to the hard contact lenses.

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CM8001 Application Exercise (15th March) http://ossarchive.adm.ntu.edu.sg/2016-17/cm8001-group-6/cm8001-application-exercise-15th-march/ http://ossarchive.adm.ntu.edu.sg/2016-17/cm8001-group-6/cm8001-application-exercise-15th-march/#respond Wed, 15 Mar 2017 07:28:46 +0000 http://ossarchive.adm.ntu.edu.sg/2016-17/cm8001-group-6/?p=95 1. Mammoth Cove National Park in Kentucky is in close proximity to the coal-fired electric utility plants in the Ohio Valley. Noting this, the 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?

Coal-fired plants release sulfur dioxide, creating sulfate particles that are responsible  for 60-85% of the poor visibility in the eastern parks.

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.

Normal rain has a pH range of 5-6. Given pH = -log[H+], the pH will be in a range of 4-5 since the national park is 10 times more acidic than the natural rain.

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

a. Hand your laundry to dry it

Hanging laundry to dry does not require the use of clothes dryer and thus less energy is required. Reducing the energy usage will decrease the need for the power companies to produce electricity via the burning of coal. This will reduce the production of acidic gases like carbon dioxide or sulfur dioxide which contributes to acidic rain.

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

All these alternatives does reduces the usage of gasoline or fuels which in turn reduces the nitrogen monoxide and carbon dioxide emission. These gases contribute to the acidity of the rain

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

Maximising the load of disherwashers and washing machines will reduce the number of run. Cutting down on such heavy power appliances reduces the energy usage which will decrease the need for the power companies to produce electricity via the burning of coal. This will reduce the production of acidic gases like carbon dioxide or sulfur dioxide which contributes to acidic rain.

d. Add additional insulation on hot water heaters and pipes

This is to reduce the heat loss to the surrounding and thus there is no need to constantly re-heat the water. This will reduce the energy usage of the heater which will decrease the need for the power companies to produce more electricity via the burning of coal. This will reduce the production of acidic gases like carbon dioxide or sulfur dioxide which contributes to acidic rain.

e. Buy locally grown produce and locally produced food.

This reduces the need to import food from oversea, cutting down on the air/land/sea transports. This will cut down on the fuel usage which in turn will decrease the acidic gases such as carbon dioxide and nitrogen monoxide being produced.


Fig 1. The effects of the production of acidic gases by man-made actions on the environment
1.

3a. Give names and chemical formulas for five acids and five bases.

For bases,

Sodium hydroxide : NaOH
Ammonium hydroxide : NH4OH
Calcium hydroxide : Ca(OH)2
Lithium hydroxide : LiOH
Magnesium hydroxide : Mg(OH)2

For acids,

Propanoic acid : CH3CH2COOH
Acetic acid :  CH3COOH
Hydrochloric acid : HCl
Sulfuric acid : H2SO4

Nitric acid : HNO3

b. Name 3 observable properties generally associated with acids and bases.

For acids they are sour, react with metal to produce H2 gas and changes blue litmus paper to red. For bases they are bitter, slippery and changes red litmus paper to blue.

4. The concerns of acid rain vary across the globe. Many countries in North America and Europe have website 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 border?

Singapore being a very small country is susceptible to acid deposition orginated from outside of Singapore’s border. Indonesia has consistently been ‘slashing-and-burning’ their forest to make way for agriculture and such actions have generated a large amount of gaseous and particulate pollutant in the atmosphere. The particulate emission produced a plume which travel towards Singapore when the the wind blows in the correct direction. This had resulted in Singapore to have very poor Pollutant Standard Index (PSI) air quality. Such particulates contain very high concentrations of SO42-, NO3 and NH4+. Upon raining, it leads to very acidic rain which is detrimental not only for the environment but also for our infrastructure. 

Also, Singapore is unable to stop the forest burning as it is Indonesia’s domestic affairs. This result in a strain diplomatic relationship between the 2 countries and as such the problem cannot be solved. This will result in prolonged acidic rain in Singapore. 

1-http://isbscienceg9.blogspot.sg/2015/03/acid-rain_6.html

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CM8001 Application Exercises (22-Feb-17) http://ossarchive.adm.ntu.edu.sg/2016-17/cm8001-group-6/cm8001-application-exercises-22-feb-17/ http://ossarchive.adm.ntu.edu.sg/2016-17/cm8001-group-6/cm8001-application-exercises-22-feb-17/#respond Thu, 23 Feb 2017 15:10:57 +0000 http://ossarchive.adm.ntu.edu.sg/2016-17/cm8001-group-6/?p=75 Q1) 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.

Ans:There are a few methods to purify water while hiking.

The first method is to boil the water. Boiling can kill many microorganism that might cause one to sick. However, it requires time and does not remove chemical contamination. Boiling also requires fuel and will release soot and CO2.

The next method is to purify the water with iodine. It is an easy and effective method that requires only 20 minutes. However, iodine should not be used long term. Pregnant women and people with thyroid conditions should avoid this method of purification. Iodine renders water bacteriological safe, but it does not remove chemical contaminants. Also, many people does not like the taste of iodine-treated water.

The third method is to purify the water by using a filtering device. Filtration has the advantage of not requiring any chemicals and remove the most microorganism that cannot be killed by boiling or iodine treatment. A good filter can pump out clean water in a few minutes and is reusable.

The most expensive method will be filtering device followed by iodine and lastly boiling of water.

The price of the method is proportionate to the effectiveness of the ability to give clean water.

Boiling Iodine Filtering Device
Cost 3 2 1
Effectiveness 3 2 1
  • 1 being the most expensive and 3 for least expensive for cost.
  • 1 being most effective and 3 for least effective for the ability to remove microorganism.

Q2) Explain why desalination techniques, despite proven technological effectiveness, are not used more widely to produce portable drinking water.

Ans:The two most commmon desalination techniques are distillation and reverse osmosis. 

Both the techniques require energy to remove salts from seawater or brackish water, and thus inherently are expensive.

If a less expensive option is available, such as hauling fresh water, it would be used instead.

Q3) 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?

Ans: The most likely major source of the lead in the drinking water is from solder in the pipe joints or from lead pipes itself.

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

Ans: Research activities should not contribute to lead in the drinking water, assuming that any lead compounds are not dumped down the drain. 

Although many undergraduate chemistry experiments used to use lead compounds, most now have been redesigned to avoid it and other toxic metal ions. The substances dumped into a sewage treatment system might end up downstream into someone else’s drinking water.

Q4) Some vitamins are water-soluble, whereas others are fat-soluble. Would you expect either or both to be polar compounds? Explain.

Ans: Only water-solble vitamins would be expected to be polar molecules. Though a fat-soluble vitamin will often have individual polar bonds or small regions of the molecule, overall this out-weighed by non-polar sections. Polar covalent bonds attract to water through hydrogen bonding and may allow the molecules to dissolve in water, while non-polar covalent bonds favor interactions with the non-polar chains in lipids.

 

 

 

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CM8001 Application Exercises (15-Feb-17) http://ossarchive.adm.ntu.edu.sg/2016-17/cm8001-group-6/cm8001-application-exercises-15-feb-17/ http://ossarchive.adm.ntu.edu.sg/2016-17/cm8001-group-6/cm8001-application-exercises-15-feb-17/#respond Wed, 15 Feb 2017 08:27:45 +0000 http://ossarchive.adm.ntu.edu.sg/2016-17/cm8001-group-6/?p=35 Q1) 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?

Ans: Even though the amount of energy leaving Earth’s surface is more than twice the amount received, Earth does not cool rapidly because the atmosphere retains much of the emitted heat energy.

 


Q2) Decide and explain whether the statement is correct or incorrect. Explain.

 pepper-and-salt

Ans: The quote is incorrect and it seems to be poking fun at people who are ignorant about global warming and don’t know the difference between weather and climate. Even thought there are  particular seasons in regions that are colder, like winter, it doesn’t mean that that earth is getting cooler. The difference between weather and climate is the measure of time. Climate describes the typical and average weather a region will have over long period of time, like 30 years or more. Weather on the describes the condition of the atmosphere over a short period of time. As such, the temporary cool winter weather will not be able to compensate for the effects of global warming, hence should not have “lowered (his) concerns about global warming”.


Q3) 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?

Ans: The design was not successful as it heated up the air around the machine, which resulted in diseases infecting the operators of the radar, causing the absorption of the microwave radiation by water in the atmosphere to interfere with the detection of the intended objects.


Q4) Now that you have studied 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)?

Ans: We believe that in the short run, air quality would be the most serious problem caused in the short run, since it affects our daily lives directly, in terms of the quality of air we breathe in. However, in the long run, we feel that stratospheric ozone depletion would be the most serious problem, as the ozone layer is essential for survival of all living things by protecting us from harmful ultraviolet (UV) rays from the sun, hence following its depletion would result in extinction of all species in the long run.

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CM8001 Application Exercises (08-Feb-17) http://ossarchive.adm.ntu.edu.sg/2016-17/cm8001-group-6/cm8001-application-exercises-08-feb-17/ http://ossarchive.adm.ntu.edu.sg/2016-17/cm8001-group-6/cm8001-application-exercises-08-feb-17/#respond Thu, 09 Feb 2017 13:05:02 +0000 http://ossarchive.adm.ntu.edu.sg/2016-17/cm8001-group-6/?p=28 From personal experience, state whether these processes are endothermic or exothermic.
Give a reason for each.

  1. A charcoal briquette burns.
  2. Water evaporates from your skin.
  3. Ice melts.

Answer:

  1. Exothermic. A charcoal briquette releases heat as it burns.

  2. Endothermic. Evaporation requires thermal energy from the surrounding. In this sense, thermal energy from your body helps the water on the skin to evaporate. When water evaporates, it takes away thermal energy from the surface of your skin, and your skin feels cooler.
  3. Endothermic. The molecules in a solid ice are held by strong intermolecular bonds. For the solid ice to melt, these bonds have to be broken. Since energy is needed to break the intermolecular bonds, ice absorbs the necessary thermal energy to do work to break the intermolecular bonds between the molecules of the solid ice. Once the intermolecular bonds are broken, the molecules can now move out of their fixed position and the ice has melted.

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

Answer:

Consider a natural gas (methane) explosion:

CH4 + 2 O2 → CO2 + 2 H2O

From the above Figure, it should be noted that the bond energies of the products are larger than those of the reactants. This will lead to a large negative net energy change indicating an exothermic reaction.


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

Answer:

Heat is a form of energy – it is the amount of thermal energy that flows from a hotter region to a colder region. Per contra, the temperature is a measurement that determines the direction of heat flow. The final temperature will be between the original temperatures of the two. Heat depends on the temperature and on how much material is present. 

Consider the following experimentation:

Prepare three small basins of water labelled A, B and C as shown below. Place your right hand into basin A and your left hand into basin C. Your right hand would feel cold while your left hand would feel warm.

capture

Remove both hands, dry them with a cloth and wait for the effects of hotness and coldness in your hands to subside. Next, place one hand at a time into basin B (your body temperature) they would feel neither hot nor cold.   

Your left hand feels warm because its gain thermal energy from the lukewarm water in basin C. Your right hand feels cold because it loses thermal energy to the cold water in basin A. The water in basin B is at the same temperature as your hands – your hands feel neither hot nor cold.

Below is a video about the Misconception about Temperature:


A premium gasoline available at most stations has an octane rating of 92. What does that tell you about: 

  1. The knocking characteristics of this gasoline?
  2. Whether the fuel contains oxygenates?

 Answer:

  1. Gasoline with an octane rating of 92 means a knocking characteristic of 92% isooctane and 8% n-heptane. A premium gasoline which has a higher octane rating has lesser tendency to cause “knocking” in engines.

  2. The octane rating does not provide any information about whether the fuel contains oxygenates. This information should be available in other labels around the pump.

 

That’s all folks wink

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My First Post http://ossarchive.adm.ntu.edu.sg/2016-17/cm8001-group-6/my-first-post/ http://ossarchive.adm.ntu.edu.sg/2016-17/cm8001-group-6/my-first-post/#respond Wed, 25 Jan 2017 07:54:45 +0000 http://ossarchive.adm.ntu.edu.sg/2016-17/cm8001-group-6/?p=10 In today lesson, 25th January 2017, I have learnt that:

  • Particles of ashes hasten the transformation of sulfur dioxide to sulfur trioxide
  • Water vapor changes from time to time and day to day
  • Nitrogen is the most abundant of exhale air

img_2291

That’s all folk wink

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My First Post http://ossarchive.adm.ntu.edu.sg/2016-17/cm8001-group-6/my-first-post-2/ http://ossarchive.adm.ntu.edu.sg/2016-17/cm8001-group-6/my-first-post-2/#respond Wed, 25 Jan 2017 07:54:34 +0000 http://ossarchive.adm.ntu.edu.sg/2016-17/cm8001-group-6/?p=11 I’ve learnt that NO2 speed up the formation of sulfuric acid from sulfur dioxide instead of the particles of ashes.

green-chemistry

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Pollution http://ossarchive.adm.ntu.edu.sg/2016-17/cm8001-group-6/pollution-3/ http://ossarchive.adm.ntu.edu.sg/2016-17/cm8001-group-6/pollution-3/#respond Wed, 25 Jan 2017 07:53:41 +0000 http://ossarchive.adm.ntu.edu.sg/2016-17/cm8001-group-6/?p=6 morning traffic in winter
 Morning  traffic

i believe that the humans walking inhale more pollutants than passengers.

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Pollution http://ossarchive.adm.ntu.edu.sg/2016-17/cm8001-group-6/pollution-2/ http://ossarchive.adm.ntu.edu.sg/2016-17/cm8001-group-6/pollution-2/#respond Wed, 25 Jan 2017 07:52:41 +0000 http://ossarchive.adm.ntu.edu.sg/2016-17/cm8001-group-6/?p=9 pollution-bad_fbd596fd1a506e77

Today I learned that dihydrogen monoxide contribute to soil erosion.

 

 

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