CategoryAll Application Exercises Posts

Application Exercise 9- 5th April 2017

 

Question 1

a)  Chemical formula for Histamine: C5H9N3

b) The amine groups circled in red make histamine soluble in water due to hydrogen-bonding.

Question 2

a) Chemical formula for the antihistamine compound: C16H21N3

b) The presence of 3 amine functional groups allows the antihistamine to compete with histamine on a functional level.

Question 3

Produce Response- Aspirin, morphine, amphetamine

Inhibitory- Estrogen, penicillin, Keflex

Question 4

a) Customers’ testimonials and the claim that their manufacturing process adheres to GMP.

b) According to Singapore’s legislative laws in relation to herbal/alternative medicines, they are not subject to pre-market approval but MUST NOT contain substances that are listed in the Poisons Act, they must adhere to the heavy metals minimum concentrations and labels/packaging  must not advertise on false claims to cure diseases completely. More can be found at the HSA website under, ‘Guidelines for Traditional Medicinal Materials’.

 

Application Exercise 7 (22/3/2017)

Qn 1. Acetone dissolves the polymer, allowing the gas of the foaming agent to escape. The polymer collapses on itself and is more dense because the gas has been removed.

 

Qn 2a. LDPE cannot be used in this application because it does not have the required strength.

Qn 2b. The molecules of HDPE must line up in a way that produces the required strength. Using a thin liner of HDPE allows sufficient flexibility.

 

Qn 3. No,  as the chains that make up a polymer can be stretched, using them to flow past each other. Paper, on the other hand will break when pulled.

 

4a) bio compatible, light weight, flexible, low cost.

4b) hard contact lenses are made from PMMA. soft lenses are made from polyacrylamide. desirable properties – transport, flexible low density, tough, easy to mould, nonreactive to chemicals on eye surface, easy to manufacture, refractive index, hydrophilic permeable by oxygen.

4c) polyacrylamide has nitrogen atoms in its structure, making it hydrophilic, keeping lens soft and flexible but educes clarity of vision.

Application Exercise 5 15/3/2017

Question 1

a) Coal plants release huge amounts of water vapor during combustion. Water vapor when cooled turns into fog.

b) The average pH of rain should be neutral which is pH = 7.

pH = 7 = -log[H+]

As pH is log scale, if the acid level is 10 times stronger that is equal to 1 pH. the pH of rainfall in the park would be pH 6.

 

Question 2

a) Don’t use dryers. Reducing the amount of electricity used by home appliances is a method of decreasing emissions that cause acid rain. Supporting renewable-energy initiatives that reduce the dependence on fossil fuels is a bigger-picture solution.  By hanging your clothes can achieve this.
b) Use your car less. By using less fuel and less energy (especially if your car is electric but your power comes from fossil fuels), there is less carbon emission . There are plenty of public transit options available in many cities, including buses and trains. Or, consider starting a carpool group with people you work or travel with often.

c)  Use your appliances less. A large portion of acid rain emissions can be attributed to power generation. This means anytime you use power that comes from gas or coal, you are unwittingly contributing to acid rain.

d) Insulate your home water heater so as to reduce the need to reheat several times. This prevents heat and cold from escaping, and you can do this by adding extra insulation between walls, insulating the attic and basement or crawl space, and putting caulking or weather stripping around windows and doors.
e) Transportation also incur carbon footprint. Trucks, planes, cars, trains, and boats that are powered by fossil fuels are a huge contributor to the sulfur dioxide and nitrogen oxides that cause acid deposition. By shopping locally at markets and stores that source their products nearby, you can reduce the transportation-related acid rain emissions being released into the atmosphere. Thereby reducing carbon footprint.

Question 3

a) Names and chemical formulas for 5 acids and bases.

Acids:

  • HCl – Hydrochloric acid
  • HNO3 – Nitric acid
  • H2SO4 – Sulfuric acid
  • HBr – Hydrobromic acidHI
  • HI – hydroiodic acid

 

Bases:

  • LiOH – Lithium Hydroxide
  • NaOH – sodium hydroxide
  • KOH – potassium hydroxide
  • Ca(OH)2 Calcium Hydroxide
  • RbOH – rubidium hydroxide.

 

b) Observable properties generally associated with acid and bases:

Acid Property #1: All acids taste sour.

Base Property #1: All bases taste bitter.

Acid Property #2: Acids turn blue litmus paper red.

Base Property #2: Bases turn red litmus paper blue.

Acid Property #3: Acids destroy the chemical properties of bases.

Base Property #3: Bases destroy the chemical properties of acids.

 

Question 4

 

Native species in singapore may be wiped out by acid rain. A study by NUS reveals that streams are more acidic after a downpour than compared to the 1990s. [Adopted from The Straits Times, Home, pB1. Available from: http://newshub.nus.edu.sg/news/0909/PDF/ACIDRAIN-st-14Sep-pB1.pdf]

Acidic precipitation can be caused by several sources:

  • natural (volcanoes)
  • man-made activities, like cars and in the generation of electricity.

Acid deposition originate from both endogenous and exogenous sources.

The burning of fossil fuels by power-production companies and industries releases sulfur into the air that combines with oxygen to form sulfur dioxide (SO2). Exhausts from cars cause the formation of nitrogen oxides. From these gases, airborne sulfuric acid (H2SO4) and nitric acid (HNO3) can be formed and be dissolved in the water vapor in the air.

Singapore is a highly developed country and can be considered a strong emitter or carbon sources However, it is relatively lower as compared to other DCs.

Application Exercise 5 (22 Feb 2017)

Question 1

  Boil Purifying Tablets Portable filter/ Purifier DIY Water Filter Evaporation Trap
Cost $0 $8.59 for 100 $20 $0
Effectiveness Kills parasites, bacteria, germs Availability limited Time consuming depends on humidity.

Question 2 
Desalination techniques:
– thermal distillation
– membrane filtration
Reasons:
– Consumes a lot of energy -> costly
– Maintenance is high
– Damaged environment (sucks in small ocean creatures)

Question 3
Part A
Major Sources from:
– Lead pipes/compartment in plumbing
– Sediments in screens
– Lead parts

Part B
Unlikely due to:
– Proper bio-hazard waste disposal
– Drinking water comes straight from plant, not exposed to other sources

Question 4

 

Water-soluble

Fat-soluble

Vitamins B, C A,D,E,F
Polarity Polar Non-polar
Explanations Energy released from interaction between polar vitamin and water molecules is sufficient to overcome hydrogen bonds. Non polar molecules cannot disrupt hydrogen bonds between water molecules.

CM8001 – Application Exercise 15/02/17

Q1: the Earth’s surface also absorbs a large amount of energy from the atmosphere

Qn 2: The quote is not justified and it’s meant to make fun of people who are ignorant about global warming and don’t know the difference between weather and climate.
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. This is why scientists use climate for statistics about earth’s temperature and whether it’s getting warmer or colder. Weather on the other hand isn’t reliable and it’s nothing more than the condition of the atmosphere over a short period of time.

Qn 3: due to the specific microwave radiation that trigger rotation of water molecules, water molecules from the atmosphere absorbed the microwave radiation as well and interfered w the detection of intended objects

Q4. Air quality is the most serious problem for us in the short run as it is the most tangible, i.e. we can actually feel how unhealthy the air is for us when we breathe.
Global warming is the ‘silent killer’ that is the most serious in the long run, as it raises temperatures gradually and, in time, will make life on Earth unliveable.

Unit 4: Energy and Combustion (Application Exercise)

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 when near the burning charcoal indicates the release of heat, thus an exothermic process.

b. Water evaporates from your skin.

The process leaves a cool sensation on one’s skin. This indicates that heat energy contributed by the human is lost to the evaporation process to break the inter-molecular forces of attraction between water molecules in liquid water and is hence an endothermic process.

c. Ice melts.

Likewise, the melting of ice is cold, indicating that heat is absorbed to overcome the inter-molecular forces of attraction between water molecules in solid ice. Hence, it is an endothermic 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.

There are 2 possible indicators of a ‘good’ explosion explained below:

a) It is easy to explode. This indicates low activation energy required to break the bonds in product molecules.

b) The explosion is huge. This indicates that a large amount of energy is released. This can only be achieved if the change in energy between the products and reactants is large, indicating that the bond strength in product molecules are very much weaker than the bond strength in reactant molecules.


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

Temperature Heat
Definition Measure of heat energy (average energy of molecular motion) A form of energy (thermal)
Relationship An increase in the amount of heat (thermal energy) will cause an increase in temperature.
Example 1 (different temperatures) A cup of cold water versus a cup of hot water

A cup of hot water would have a higher temperature than a cup of cold water. Intuitively, we know that a cup of hot water has more thermal energy (because it is hot). Hence, more heat energy (for the same volume) would indicate a higher temperature.

Example 2 (different volumes) A bathtub full of water versus a cup full of water

While both may have the same temperature (say 30 degrees Celsius), the bathtub full of water would have more thermal energy by virtue of the fact that it has a larger volume and hence more energy (thermal).


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 indicates a knocking characteristic of 98% isooctane and 2% heptane. Its ability to combust without causing knocking is similar to pure isooctane and  greatly higher than pure heptane. 

Practically, whether this causes knocking would also depend on the individual vehicle’s engine compression ratio.

b. whether the fuel contains oxygenates?

To our present knowledge, there appears to be no relationship between octane number and the presence of oxygenates. 

Ozone 38

The ozone layer protects Eart from harmful UV radiation. It has a basic chemical structure O3.

o3

 

 

 

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