Incomplete combustion happens when the supply of air or oxygen is poor. Water is still produced, but carbon monoxide and carbon are also produced. Less energy is released than during complete combustion.
For example, here is one possible equation for the incomplete combustion of propane:
propane + oxygen → carbon monoxide + carbon + water
C3H8 + 3O2 → 2CO + C + 4H2O
The carbon is released as fine black particles. We see this in smoky flames, and it is deposited as soot. Soot can cause breathing problems and it blackens buildings. It may block boilers and other appliances, or cause a fire.
Carbon monoxide is a toxic gas. It is absorbed in the lungs and binds with the haemoglobin in the red blood cells. This reduces the capacity of the blood to carry oxygen. Carbon monoxide causes drowsiness, and affected people may fall unconscious or even die.
sulfur + oxygen → sulfur dioxide
S(s) + O2(g) → SO2(g)
Sulfur dioxide dissolves in water in the clouds to form sulfurous acid:
SO2(g) + H2O(l)→ H2SO3(aq)
Oxygen in the air reacts with sulfurous acid to form sulfuric acid:
H2SO3(aq) + ½O2(g) → H2SO4(aq)
Explain why sulfurous acid is oxidised when it forms sulfuric acid.
Sulfurous acid reacts with oxygen and gains oxygen in the reaction.
Acid rain damages the natural and built environment. For example, it:
High temperatures are reached when fuels are burned in engines. At these high temperatures, nitrogen and oxygen from the air can react together to produce oxides of nitrogen. For example:
nitrogen + oxygen → nitrogen monoxide
N2(g) + O2(g) → 2NO(g)
Nitrogen monoxide gas can be oxidised further in air to produce nitrogen dioxide gas, NO2.
These two oxides of nitrogen are together represented by the formula NOx. They are atmospheric pollutants. They can react in sunlight with other substances to produce a hazy, harmful smog. Nitrogen dioxide is toxic. It can cause bronchitis and other lung diseases. It also dissolves in water in the clouds, forming an acidic solution that contributes to acid rain.
Write a balanced equation for the reaction between nitrogen monoxide and oxygen, forming nitrogen dioxide. Include state symbols in your answer.
2NO(g) + O2(g) → 2NO2(g)