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Neutralising the Threat of Acid Rain

Question 1 (a)

Coal-fired plants release sulphur dioxide, creating sulphate particles that are responsible for60 to 85 percent of the poor visibility in eastern parks. 

Question 1 (b)

Normal rain has a pH range of 5–6, so if the rainfall in this park is 10 times more acidic, the pH range must be 4–5.

Question 2 (a)

By hanging outside, you are not using the dryer. As using dryer requires energy consumption, by not using it, we are reducing the production of electricity.

Question 2 (b)

By using the public transport, more people share the energy and fuel consumption as compared to them having their own cars.

Question 2 (c)

Avoid using the machine multiple times as small loads can be reduced with bigger loads, reducing energy consumption.

Question 2(d)

Preventing heat and cold from escaping, reducing energy use.

Question 2 (e)

By buying locally produced produce, there is no need to ship the goods around with ships, trucks, planes, which are huge contributors of SO2 and NO2 that causes acid rain.

Question 3

Acids Bases
Hydrochloric acid (HCL) Sodium Hydroxide (NaOH)
(Sulphuric acid (H2SO4) Potassium Hydroxide (KOH)
Nitric acid (HNO3) Ammonium Hyrdoxide (NH4OH)
Carbonic Acid (H2CO3) Magnesium Hydroxide (Ma(OH)2)
Phosphoric acid(H2PO4) Calcium Hydroxide (Ca(OH)2)
Turn blue litmus paper pink

Tastes sour

Conduct electric current

 Turn red litmus paper blue

Tastes bitter

Slippery feel in water

Question 4

Native species may be wiped out in Bukit Timah Nature Reserve. The acidity of the streams in the nature reserve is more acidic as compared to 20 years ago. The population of certain animal species have decreased and crabs have developed harder shells.

Acid deposition originates both inside and outside of Singapore. Within Singapore, industrialisation and presence of aerosols cause acid deposition. Transboundary sources include forest fires from Indonesia. Forest fires produce carbon dioxide and sulphur dioxide, which combines with rain to make carbonic acid and sulphuric acid.

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Energy From Combustion

My favourite module is here again, today we learnt about energy from combustion!! After learning so much, this is the questions given by our professor and I shall post them online!cool

Question  1

Endothermic processes absorb energy. The  net energy change is positive. Exothermic processes releases energy and the net energy change is negative.

(a) exothermic, as charcoal releases heat when it burns and heat is a form of energy.

(b) endothermic, as water molecules need energy to break their bonds. Energy is absorbed when bonds are broken.

(c) endothermic, solid is converted to liquid, and energy is absorbed to  break the bonds.

Question 2

In order to have a good explosion, a large amount energy should be released. The energy released is determined by the difference in bond strength between the products and reactants. Therefore, to have a big explosion, the bond strength of products should be much higher than the bond strength of the reactants.

Consider a natural gas (methane) explodes:

CH4 + 2O2 -> CO2 + 2H2O

This reaction gives out a very large amount of energy during the process. The bond strength of the products  is higher than that of the reactants .

Question 3

Temperature is the determines the direction of heat flow. Heat is energy which flows from a hotter to a colder object. Imagine putting a ice cube into a hot water, the temperature of the hot water is higher than that of the ice.  Therefore, heat energy is transfered from the hot water to the ice cube. This causes the temperature of hot water to fall and the temperature of the ice cube to rise. This would continue until both are of the same temperature.

The heat energy of an object is determined by the mass, temperature and specific heat capacity. Using an example to explain, imagine a large pot and a small bowl sitting on your dinning room table. Both are filled to the brim with hot soup of the same temperature. The small bowl of soup will reach room temperature faster than the big pot of soup despite the fact that they are of the same temperature. This is due to the difference in heat energy due to the differing masses of the big pot of soup and the small bowl of soup.

Question 4

a) an octane number of 98 means a knocking characteristic of 98% isooctane and 2% heptane.

b) the information given does not tell us anything about whether the fuel contains oxygenates.

That’s all for this week, can’t wait for next week 🙂