1.1 Global Warming and Climate Change

Question 1

Describe the action of the common greenhouse gases, CO2 and CH4, to maintain a steady temperature in the Earth’s atmosphere.

Answer 1

1. Infra-red rays from the sun are reflected by the Earth’s surface
2. IR rays are absorbed by greenhouse gases in the atmosphere
3. More heat is present in the Earth’s troposphere
4. Therefore, higher average temperatures

Question 2

How does an increase in the concentration of greenhouse gases contribute to the Enhanced Greenhouse Effect?

Answer 2

More gases present in the atmosphere
TF, more heat absorbed
TF, higher average temperatures

Question 3

How can we reduce CO2 emissions?

Answer 3

Decreasing use of fossil fuels
Using alternative energy sources
Using less energy
Planting more trees (This is carbon neutral)

Question 4

What are the consequences of climate change for the environment?

Answer 4

Acidification of oceans
TF, Skeletons and shells of marine animals are vulnerable

Polar ice caps melting
TF, Rising sea levels
TF, Flooding of land

More severe weather
TF, Hurricanes and destructive changes in climate

Question 5

What causes Ocean Acidification?

Answer 5

Non-metallic oxide (TF, acidic) CO2 is non-polar and has a low solubility in H2O.
CO2 react with H2O to form carbonic acid (a weak acid)

Question 6

Equations for Ocean Acidification - Forming weak carbonic acid (3 steps)

Answer 6

STEP 1: Due to low polarity, CO2 not soluble
CO2 (g) –> (equilibrium) CO2 (aq)
STEP 2: CO2 reacts with water molecules to form carbonic acid
CO2 (aq) + H2O (l) –> (equilibrium) H2CO3
STEP 3: Carbonic acid is a weak acid and incompletely ionises
H2CO3 (aq) –> 2H+ (aq) + CO3 (-2)(aq)
H2CO3 (aq) –> 2H3O+ (aq) + CO3 (-2)(aq)

Question 7

What is pH?

Answer 7

The pH of an aqueous solution refers to the concentration of H+

1 - very acidic —–> 14 - very basic

Question 8

What is the relationship between pH and concentration?

Answer 8

pH = -log [H+]

[H+] = 10^-pH

Question 9

What is the relationship between pOH and concentration?

Answer 9

pOH = -log [OH-]

[OH-] = 10^-pOH

Question 10

What is the relationship between pH and pOH?

Answer 10

pH + pOH = 14

Question 11

Which acids will completely ionise?

Answer 11

A strong mono-protic acid will completely ionise and there the concentration of acid equals the concentration of H+.

With a strong diprotic acid, the concentration of [H+] will be twice that of the acid.

Question 12

What are the equations for carbonates reacting in acid conditions? Shells of marine organisms will react when ocean become more acidic.

Answer 12

CO3 (2-) + 2H+ –> CO2 + H2O