2.92 - Atmospheric Pollution

What is CO (Carbon Monoxide) - Give 4 properties

• Colourless

• Odourless

• Non-irritating

• Very poisonous has

What process is carbon monoxide a result of

• Incomplete combustion of fuel - when natural gas, coal or wood burns in a limited supply of air

Name 2 processes that produce CO through incomplete combustion

• Vehicular exhaust - Incomplete combustion of petrol (or diesel)

• Cigarette smoking

Why is carbon monoxide very dangerous for humans

because it combines readily and permanently with haemoglobin in red blood cells, forming carboxyhaemoglobin. This prevents normal gaseous exchange, such as the uptake of oxygen and the release of carbon dioxide. As a result, the blood cannot deliver oxygen to the body, and the person may experience headaches, dizziness, and sluggishness.

What are 3 ways to remove/reduce carbon monoxide

• Catalytic converters are fitted to the exhausts of many cars. The catalysts will oxidize carbon monoxide in the exhaust gases to carbon dioxide

• New fuels may be used in the future (e.g alcohol which burns more cleanly than hydrocarbons)

• Vehicle engines can be tuned to take in more air and only produce carbon dioxide and water. However, this increases the formation of oxides of nitrogen

What is a combustion reaction

A chemical reaction in which a substance reacts rapidly with oxygen to produce heat and light

What are all fossil fuels made up of

Hydrogen and Carbon → hydrocarbons

What are the 2 types of combustion a hydrocarbon can undergo?

1. Complete combustion

2. Incomplete combustion

Differentiate between complete combustion and incomplete combustion

1. Complete combustion: fuels undergo this type of combustion when there is a plentiful supply of oxygen

1. Incomplete combustion: fuels undergo this type of combustion when there is not a sufficient amount of oxygen

Differentiate between the reactants and products of complete and incomplete combustion

1. Complete combustion:

hydrocarbon + oxygen → water vapour + carbon dioxide

1. Incomplete combustion

hydrocarbon + oxygen (limited) → water vapour + carbon monoxide

Differentiate between the colour of flame during complete and incomplete combustion

1. Complete combustion - clean blue flame

2. Incomplete combustion - yellow sooty flame

Differentiate between the amount of heat energy released during complete and incomplete combustion

1. Complete combustion: most heat energy released

2. Incomplete combustion: less heat energy released

This diagram shows an experiment to determine the products produced when methane is burnt it a plentiful supply of oxygen, hence when it undergoes complete combustion.

Methane is lit, air pump (provides oxygen) is switched on:

Explain what observations are noted

• A colourless liquid condenses in the U-tube

• The limewater turns milky

How can the colourless liquid be tested to confirm its water

By adding anhydrous copper(II) sulfate, which is white, but will turn blue (hydrated copper(II) sulfate) in the presence of water

What does the limewater turning milky show

That carbon dioxide was produced