Fuels used in cars often have sulfur compounds removed.

Fuels used in cars often have sulfur compounds removed.

Explain how the combustion of these fuels in car engines still leads to the formation of acid rain?

The pressure and temperatures inside the cars engine cause the oxygen and hydrogen in the engine to react to create oxides of nitrogen. The two pollutants made inside the engine are NO and NO2. These two are grouped together and called NOx. NOx gases in the air cause acid rain and react with other pollutant in the air to create photo chemical smog.

2.28 describe a physical test to show whether water is pure.

Pure water boils at 100 ^OC and freezes at 0^OC.  You can check these to confirm the identity of the liquid.

2.27 describe the use of anhydrous copper(II) sulfate in the chemical test for water

Anhydrous copper(II) sulfate is white. It turns blue, forming the hydrated salt, when water is added.  This is an exothermic reaction.

CuSO4(s) + 5H2O(l) → CuSO4.5H2O(s)

See also section 4.23 (reversible reactions)