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AE9 (5/4/17)

1.

a. C5H9N3

b. The -NH2 at the extreme left end.

c. The amine group will contribute the most to the polarity of the molecule. This is the part that will interact the most with polar solvents such as water!

 

2.

a. C16N3H21

b. Both compounds have nitrogen-containing rings but they are of vastly different sizes which affects their properties.

 

3.

Antibiotics- Keflex, Penicillin

Other drugs-  Aspirin, Morphine, Estrogen, Amphetamine

 

4.

a. Bioactive ingredients found in herbal or alternative medicines are increasingly being clinically tested and documented to prove their effectiveness. Manufacturers are also seeking to improve quality control by having a scientific appraisal process, standardised production technology and as well as stringent quality control procedures. Research grants have been offered for formal medical studies conducted by medical researchers on the combined usage of herbal supplements and commonly used drugs such as aspirin, and level 1 clinical trial results have shown that combination usage of the medicines have no adverse effect.

b. Under Singapore’s Health Products Act and the Medicines Act, it is mandatory for all domestic manufacturers and assemblers of both therapeutic and traditional chinese medicine to comply with Good Manufacturing Practice (GMP) laid out by the Health Science Authority (HSA). All overseas manufactures are expected to comply with the local GMP standards as well. The GMP ensures that the production process of the medicinal products are consistent with the quality standards that is appropriate for their intended use. Singapore also adopts a post-market surveillance system consistent of two distinct components. First, regular samples and tests of products found in the market are conducted. Second, a local network of healthcare professional and global regulatory partners help to monitor and pick up advanced signs of any problematic health products that are causing adverse reactions. This two pronged approach helps Singapore to stay ahead and issue early recalls of harmful alternative medicine products.

 

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AE 7 (22/03/17)

  1. Acetone will dissolve the polymer and the gas escapes from the foaming agent. Then, the polymer becomes smaller and denser when the gas escapes.
  2. LDPE cannot be used in the circumstance as it is not strong enough to withstand the potential pressures it would be subjected to. HDPE on the other hand is a much stronger polymer because of the way the layers of monomers are arranged. Using a thin layer of HDPE overcomes the its rigidity allows the gloves to be tough as well as flexible.
  3. No it does not. This occurs in plastic because the intermolecular bonds between the layers of plastic are weak enough to cause them to slide over one another. This ability is not facilitated by the rigid intermolecular bonds in paper (as it is not a pure polymer) Hence the paper does not exibit this property of stretching under pressure.
  4. First, it has to be non-toxic so that it does not adversely affect the patient. Next, it cannot be soluble as the human body contains water, fats and other solutions that could compromise the structural integrity of the implant. Also, it has to be stable once implanted into the body. Lastly, it should not be too expensive so that it can be available to the majority of patients. Contact lenses are made from PMMA, an early polymer developed specifically for this purpose. RGP and HEMA are also used in newer designs. Contact lenses should be non-toxic, clear, permeable to oxygen and comfortable to wear. Hard contact lenses are made from PMMA and are made to be more lasting. Soft contact lenses are based on silicon polymers which tend to be more comfortable and more permeable to oxygen.
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Chemical concept

What is HAZE? HAZE is made up of adequate smoke, dust, moisture, and vapour suspended in relatively dry air.  When weather conditions prevent the dispersal of smoke and other air pollutants, they concentrate and form a usually low-hanging shroud that impairs visibility and may become a respiratory health threat. Industrial pollution can result in a dense haze, which is known as smog. HAZE pollution can be said to be “transboundary” if its density and extent is so immense in a source that it remains at measurable levels after crossing into another country’s airspace.

What is AIR POLLUTANT? An air pollutant is a substance in the air that can have detrimental effects on humans and the ecosystem. The substance can be solid particles, liquid droplets, or gases. A pollutant can be of natural origin or man-made. Pollutants are classified as primary or secondary. Primary pollutants are harmful substances that are emitted directly into the atmosphere. Secondary pollutants are harmful substances formed in the atmosphere when a primary air pollutant reacts with substances normally found in the atmosphere or with other air pollutants. Some pollutants may be both primary and secondary: they are both emitted directly and formed from other primary pollutants.

Major PRIMARY POLLUTANTS produced by human activity include:

  1. Carbon monoxide (CO) – CO is a colourless, odourless, toxic yet non-irritating gas. It is a product of incomplete combustion of fuel such as natural gas, coal or wood. Vehicular exhaust is a major source of carbon monoxide.
  2. Sulfur oxides (SOx) – particularly sulfur dioxide, a chemical compound with the formula SO2. SO2 is produced by volcanoes and in various industrial processes. Coal and petroleum often contain sulfur compounds, and their combustion generates sulfur dioxide. Further oxidation of SO2, usually in the presence of a catalyst such as NO2, forms H2SO4, and thus acid rain.This is one of the causes for concern over the environmental impact of the use of these fuels as power sources.
  3. Nitrogen oxides (NOx) – Nitrogen oxides, particularly nitrogen dioxide, are expelled from high-temperature combustion and are also produced during thunderstorms by electric discharge. They can be seen as a brown haze dome above or a plume downwind of cities. Nitrogen dioxide is a chemical compound with the formula NO2. It is one of several nitrogen oxides. One of the most prominent air pollutants, this reddish-brown toxic gas has a characteristic sharp, biting odour.
  4. Carbon dioxide (CO2) – This is by far the most emitted form of human-caused air pollution. Although CO2 is currently only about 405 parts per million in earth’s atmosphere, billions of metric tonnes of CO2 are emitted annually by burning of fossil fuels.The CO2 increase in earth’s atmosphere has been accelerating.
  5. Particulates, alternatively referred to as particulate matter (PM), atmospheric particulate matter, or fine particles, are tiny particles of solid or liquid suspended in a gas. In contrast, aerosol refers to combined particles and gas. Some particulates occur naturally, originating from volcanoes, dust storms, forest and grassland fires, living vegetation, and sea spray. Human activities, such as the burning of fossil fuels in vehicles, power plants and various industrial processes also generate significant amounts of aerosols. Averaged worldwide, anthropogenic aerosols—those made by human activities—currently account for approximately 10 percent of our atmosphere. Increased levels of fine particles in the air are linked to health hazards such as heart disease, altered lung function and lung cancer.
  6. Volatile organic compounds (VOC) – VOCs are a well-known outdoor air pollutant. They are categorised as either methane (CH4) or non-methane (NMVOCs). Methane is an extremely efficient greenhouse gas which contributes to enhanced global warming. Other hydrocarbon VOCs are also significant greenhouse gases because of their role in creating ozone and prolonging the life of methane in the atmosphere. This effect varies depending on local air quality. The aromatic NMVOCs benzene, toluene and xylene are suspected carcinogens and may lead to leukaemia with prolonged exposure. 1,3-butadiene is another dangerous compound often associated with industrial use.

SECONDARY POLLUTANTS include:

  1. Ground-level ozone (O3) formed from NOx and VOCs. Ozone (O3) is an essential constituent of the troposphere. It is also an important constituent of certain regions of the stratosphere commonly known as the Ozone layer. Photochemical and chemical reactions involving it drive many of the chemical processes that occur in the atmosphere by day and by night. At abnormally high concentrations brought about by human activities (largely the combustion of fossil fuel), it is a pollutant and a constituent of smog.
  2. Particulates created from gaseous primary pollutants and compounds in photochemical smog. Smog is a type of air pollution. Classic smog results from large amounts of coal burning in an area caused by a mixture of smoke and sulfur dioxide. Modern smog does not usually come from coal but from vehicular and industrial emissions that are acted on in the atmosphere by ultraviolet light from the sun to form secondary pollutants that also combine with the primary emissions to form photochemical smog.
  3. Peroxyacetyl nitrate (C2H3NO5) – similarly formed from NOx and VOCs.

 

References:

  1. Haze. Wikipedia. 2017 Mar 22 [accessed 2017 Apr 8]. https://en.wikipedia.org/wiki/Haze
  2. Vaswani K. Singapore haze hits record high from Indonesia fires. BBC News. 2013 Jun 21 [accessed 2017 Apr 8]. http://www.bbc.com/news/world-asia-22998592
  3. About Haze. About Haze. [accessed 2017 Apr 8]. http://www.haze.gov.sg/about-haze
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Implications of Air pollution

Implications of Air Pollution

Air pollution is one of the world’s biggest problem as it can have adverse effects on human health and the environment. Some examples of air pollutants(which are also present in haze) are given below:

Carbon monoxide (CO), sulfur dioxide (SO2), Sulfur Trioxide (SO3), Nitrogen oxide (NOx) and Ozone (O3).

Health effects:

Carbon monoxide (CO):

Formed when hydrocarbon fuels are burned in a place with not enough oxygen to produce Carbon Dioxide. CO is colourless, odourless and tasteless. In high concentration, it can cause CO poisoning, giving symptoms such as headache, vomiting, nausea, etc. This is due to its ability in displacing oxygen in our blood as it binds to haemoglobin 250 times better than oxygen to form carboxyhemoglobin, resulting in the decrease of oxygen supply to our body. A 50% of carboxyhemoglobin can cause coma, seizure and even death.[1]

https://www.cdc.gov/features/timechangecodetectors/

 

 

sulfur dioxide (SO2):

Usually produced from the burning of fossil fuel e.g. Coal. It is a pungent toxic irritant and can cause temporary breathing difficulties when high concentration of SO2 is inhaled. [2]

 

https://yamkin.files.wordpress.com/2014/09/sulfur-dioxide-alert.png

 

Nitrogen oxide (NOx) and ozone (O3):

NOx such as Nitrogen monoxide (NO) and Nitrogen Dioxide (NO2) are produced at high temperature in the presence of O2 and N2. When NO (very toxic) is formed, it will quickly oxidize in air to form NO2. NO2 is a pungent irritant that can affect skin and cause burns. High concentration of gaseous NO2 have the ability to diffuse and dissolve in our lungs, causing some chemical reaction to occur which produces products that are reactive that can cause inflammation, reduced immune response and affect the heart.[3]

 

When NO2 is exposed to sunlight, it undergoes reaction to give NO and O atom. The O atom will then react with an oxygen molecule giving rise to ozone (O3) a secondary pollutant in our troposphere. O3 has a acrid smell and is capable of destroying living tissues. It can affect respiratory tissue causing chest pain, coughing, sneezing and pulmonary congestion.

 

Environmental effects:

Some of these air pollutants such as nitrogen oxides and sulfur oxides can combine with water droplets during rain which result in acidic rain. Acidic rain can cause damage to animals, crops and infrastuctures.

NO2 reacts with OH to form nitric acid which contributes to acid rain.

SO2 reacts with O2 to form Sulfur trioxide (SO3). SO3 can react with water to form sulfuric acid which can also contribute to acidic rain.

Acidic rain can cause the drop in pH of lakes and streams. The United States Environmental Protection Agency’s (EPA) website states: “Of the lakes and streams surveyed, acid rain caused acidity in 75% of the acidic lakes and about 50% of the acidic streams”. At pH lower than 5, most fish eggs will not hatch and lower pHs can kill adult fish, insects and birds in the ecosystem are also affected. [4]

 

Forests are also damaged as acid rain reduces the amount of nutrients in soil and releases aluminium making it difficult for trees to take up water. Leaves are also damaged by acid.

 

Solutions to for air pollution:

Since most of these pollutants are anthropogenic emission, there are things that we can do to reduce it:

  • Use public transport
  • https://pbs.twimg.com/media/CV3DMGuUEAA1baM.png

 

 

  • Conserve energy e.g. switching off lights when not in use
  • https://s-media-cache-ak0.pinimg.com/originals/6a/80/3c/6a803cfef6eee367103f9b79acb280ec.jpg

 

 

  • Using clean energy e.g solar, wind, etc.
  • https://cleanchoiceenergy.com/assets/img/how-it-works-2.png

 

 

  • Using energy efficient devices

https://www.asdreports.com/media/pr_444.jpg

 

By doing these, we can reduce the amount of eletrcity generated and reduce the amount of coal being burned leading to a drop in amount of air pollutants like NO2 and SO2 being produced. [5]

Implication References:

[1] https://en.wikipedia.org/wiki/Carbon_monoxide

[2] https://en.wikipedia.org/wiki/Sulfur_dioxide

[3] https://en.wikipedia.org/wiki/Nitrogen_dioxide#Toxicity

[4] https://en.wikipedia.org/wiki/Acid_rain

[5] http://www.conserve-energy-future.com/current-environmental-issues.php

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Application Exercise (15 March 2017)

1a) Coal fired plants have been linked to poor visibility due to the fact that the plants release sulfur dioxide which eventually become sulfate particles that are responsible for the poor visibility.

1b) As the benchmark values for normal rain is between pH 5 and 6, the pH of rainfall in the park should fall between the values of pH 4 to 5

 

2a) If we hang our laundry to dry, we won’t be needing to use the dryer which saves electricity and electricity comes from burning of fossil fuels. Thus lowering the production of SOx and NOx which contributes to acid rain.

2b) By walking or taking the public transport, we will be reducing the number of cars on the roads. The highest NOx emissions are generally found in places with heavy automobile traffic. Thus, by reducing the number of cars, it reduces the production of NOx emssions.

2c) Washing more clothes at one go with the washing machine is more “eco-friendly” because it produces lesser SOx and NOx as compared to using the washing machine more frequently.

2d) By adding additional insulation on hot water and pipes, lesser electricity is needed to keep the water hot thus burning lesser fossil fuels.

2e) By purchasing local products, we discourage imports from overseas thus fewer airplanes required and fewer NOx and SOx produced.

 

3a) The names and chemical formulas for five acids and bases are as followed:

Acids

  1. Sulfuric acid, H2SO4
  2. Phosphoric acid, H3PO4
  3. Nitric acid, HNO3
  4. Hydrochloric acid, HCl
  5. Carbonic acid, H2CO3

Bases

  1. Ammonium hydroxide, NH4OH
  2. Ammonia, NH3
  3. Lithium hydroxide, LiOH
  4. Sodium hydroxide, NaOH
  5. Potassium hydroxide, KOH

3b) Acids – Tastes sour, Turns blue litmus paper red, observed pH value of less than 7 using pH meter

Bases – Slippery, Bitter, Turns red litmus paper blue

 

 

4) Acid Rain affects our reservoir health and metallic structures such as bridges and sculptures. An urban population leads to high NO production due to cars and other vehicles . However, Singapore has made it compulsory (by law) to have catalytic converters installed in vehicles. This significantly reduces NO production. Therefore, most of the acid deposition occurs from outside Singapore’s borders, in areas where catalytic converters are not installed in all cars and NO pollution is rampant.

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AE 5 (22nd Feb)

  1. Boiling the water should kill off most bacteria and pathogens. Conversely, we can use iodine tablets to make the water safe for consumption. Boiling requires time and fuel  but is a rather inexpensive method of purifying water. On the other hand, iodine tablets are more expensive but are more convenient. Boiling is similar to the industrial distillation process, as it is the key process in this form of water purification.

 

2. Firstly, it is an energy intensive process which requires many resources. Secondly, it needs to be located near the sea in order to maximise transport efficiency which may not always be a viable option. These limitation are often overcome by using other water purification techniques.

 

3a. Corrosion of lead pipes or solder in drinking fountains or water storage tanks.

3b. No. There are separate pipes for drinking water and waste water. Furthermore, waste products from research activities should be specially handled and safely disposed of.

 

4. Water-soluble vitamins should be polar compounds while fat-soluble vitamins should be non polar. It is important to note that only polar solutes can dissolve in polar solvents such as water. Similarly, only non polar compounds can dissolve in non polar solvents such as fat. Therefore we can come to such a conclusion.

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Application exercise 4: unit 5 (15/02/17)

  1. From the example, we can see that the amount of energy emitted form the surface is more than the energy striking the Earth’s surface. However, the Earth does not cool rapidly because the Earth’s surface absorbs a great amount of energy from the atmosphere.
  2. The understanding of the term “global warming” is wrong. Based on the statement, it assumed that global warming is only about the warming of atmosphere and snowing would mean that global warming is not much of a threat. However, global warming also causes heavier precipitation events such as heavier snow fall or unnatural events like snowing in the middle of summer.
  3. The design was unsuccessful because the absorption of microwave radiation by atmospheric water hinders with the detection of intended items.
  4. In the short term, air quality is the most serious problem because it has direct adverse impact to our health and it definitely has faster effects as compared to the other 2. In the long run, however, global warming is the most serious problem because global warming carries massive implications for a lot of processes. The detrimental effects of global warming trickle down to other aspects which affects our air quality and our way of life. Global warming will also increase the incidents of extreme weather events such as higher number of typhoons and hurricanes. (Hurricane Katrina :((((( )
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Application exercise 3: unit 4 (08/02/17)

  1. a) Exothermic, heat is given off because it burns. b) endothermic, gains heat from body heat to evaporate c) endothermic, gains heat from surrounding.
  2. Good explosion is a rapid high energy reaction (very exothermic). For this condition to arise, the bond energies of the products have to be larger than those of the reactants. This will lead to a large negative net energy which shows an exothermic reaction.
  3. Heat is a consequence of motion at the molecular level while temperature is a measure of the average speed of that motion. An everyday example would be the usage of a metal spoon in a hot soup. The heat of the soup gets transferred to the spoon. There’s a difference in temperature between the bowl of the spoon and the handle of the spoon so heat travels from the bowl to the handle. The higher the heat energy, the faster the transfer.
  4. a) An octane number of 98 means a knocking characteristics of 98% of issoctane and 2% heptane. b)The octane rating shows us nothing about whether the fuel contains oxygenates.
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1st lesson of cm8001

 

Carbon monoxide is a silent killer.

It binds 250times better to red blood cell than oxygen does.

Reducing the amount oxygen being carried around in the body.

 

img_2202

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Learning points for Unit 1:The Air We Breathe

Molecules in the air include primarily nitrogen and oxygen as well as water, carbon dioxide, ozone, and many other compounds in trace amounts, some created naturally, others the result of human activity.

In addition to gases, the atmosphere contains extras such as smoke, dust, acid droplets, and pollen.

The composition of the atmosphere changes constantly and depends on the season, weather, time of day, latitude, longitude, elevation, and geography.

img_2527img_2527