C1 - Air Quality

Question 1

The atmosphere contains about __% nitrogen, __% oxygen, __% argon and other noble gases.

Answer 1

The atmosphere contains about 78% nitrogen, 21% oxygen, 1% argon and other noble gases.

Question 2

Describe the Evolution of the Atmosphere.

Answer 2

Note: When carbon dioxide dissolved in oceans, it reacts with salts to form insoluble calcium carbonate.

The levels of Nitrogen went up because of the reaction between ammonia (NH₃) and Oxygen (O₂) (Ammonia + Oxygen –> Nitrogen monoxide + water). Nitrogen is not very reactive and when formed, is not easily removed from the atmosphere.

Question 3

How is Carbon dioxide harmful?

Answer 3

HARMFUL TO: Environment.

• It traps heat in the Earth’s atmosphere (It’s a greenhouse gas).

Question 4

How are Nitrogen oxides harmful?

Answer 4

HARMFUL TO: Environment and Humans.

• Causes acid rain.
• Causes breathing problems and can make asthma worse.

Question 5

How is Sulfur dioxide harmful?

Answer 5

HARMFUL TO: Environment.

• Causes acid rain.

Question 6

How are Carbon particulates harmful?

Answer 6

HARMFUL TO: Environment and Humans.

• They make buildings dirty.
• Can worsen asthma and lung infections.

Question 7

How is Carbon monoxide harmful?

Answer 7

HARMFUL TO: Humans.​

• Prevents the blood from carrying oxygen.

Question 8

What is the word equation for complete combustion?

Answer 8

Hydrocarbon + Oxygen –> Carbon dioxide + Water.

Question 9

What is the word equation for incomplete combustion?

Answer 9

Hydrocarbon + Oxygen –> Carbon monoxide + Carbon + Water.

Question 10

How are NO_x gases formed?

Answer 10

High temperatures (e.g: In a car engine) can cause nitrogen to react with oxygen as follows:

N₂ + O₂ –> 2NO

Nitrogen monoxide is then oxidised:

2NO+O₂ –> 2NO₂.

Question 11

How is sulfur dioxide removed from power stations?

Answer 11

Via wet scrubbing with either a spray of calcium oxide and water or using seawater.

Question 12

How can carbon monoxide emissions be reduced from cars?

Answer 12

• By using low-sulfur fuel in cars with a modern, fuel-efficient engine.
• Legal limits for exhaust emissions, enforced via MOT tests.
• Using public transport.
• Fitting cars with catalytic converters.
• Using biofuels.

Question 13

What equations occur in a catalytic converter?

Answer 13

• 2CO + O₂ –> 2CO₂.
• 2NO + 2CO –> N₂ + 2CO₂.

Question 14

You may be asked to consider whether or not data is an outlier.

What must you consider in such a situation?

Answer 14

• Was it caused by equipment/human error?
• How far different is it from the other values?
• How much variation is there in the other values/how big the range is.
• Was there different conditions?

Question 15

What pollutant(s) are measured in ppm (Parts per million)?

Answer 15

• Carbon dioxide.

Due to small amounts in the air.

Question 16

What pollutant(s) are measured in ppb (Parts per billion)?

Answer 16

• Carbon monoxide.
• Nitrogen oxides.
• Sulfur dioxide.

Due to larger abundance in the atmosphere.

Question 17

How can we improve power stations?

Answer 17

• Reduce electricity use - new electrical products use less electricity. Don’t leave products on standby.
• Burning oil and gas makes less sulfur dioxide than burning coal.
• Sulfur can be removed from oil and gas before it is burnt, but it is harder to remove from coal.
• Cleaning waste gases.
• Power stations can remove solid particulates using electrostatic filters.
• Sulfur dioxide can be removed from waste gases by flue gas desulfurisation.

Question 18

Name a suitable alternative to fossil fuels, with advantages and disadvantages and give examples of this.

Answer 18

Biofuels, made from plants. They are carbon neutral however, large areas of land are needed. Furthermore, they are renewable.

e.g) Wood chips, palm oil and alcohol made from sugar.

Question 19

Why do we take multiple measurements?

Answer 19

• A single result may vary, so repeats are needed.
• A result which is very different might be an outlier - an incorrect result.
• Calculating the mean (average) is a good way to estimate the true value.

Question 20

Name 4 methods of reducing power station pollution.

Answer 20

• Using less electricity.
• Removing sulfur and other toxic chemicals from gas, coal and oil before burning.
• Using alternative renewable sources.
• Removing sulfur dioxide from flue (chimney) gases by wet scrubbing.

Question 21

What is the general equation for:

Metal + Oxygen –> _________.

Answer 21

Metal + Oxygen –> Metal oxide.

Question 22

How do you find the percentage of oxygen in the air?

Answer 22

General: By passing air over heated copper.

Explanation:

You should measure a known volume of air in a glass syringe, and measure the decrease in volume as the oxygen reacts with it. The following reaction will occur:

2Cu + O₂ –> 2CuO.

Continue pushing the air between the two syringes until you get repeat readings.

Note that there will be some error due to the air being in the tube containing the copper turnings. Also, it is important to let the apparatus cool down at the end of the experiment, else the final reading will be too high.

The cm of oxygen you have in the syringe that previously contained the air when you conducted the experiment is the air that must’ve reacted with oxygen. This should be 79cm, and therefore 21cm must have reacted, and there must be 21% oxygen.

Question 23

Name the 4 pollutants.

Answer 23

• Carbon dioxide.
• Carbon monoxide.
• Nitrogen oxides.
• Sulfur dioxide.

Question 24

What type of pollutant is acid rain?

Answer 24

An indirect pollutant.