If food is kept in the fridge, the food will keep longer because the low temperature will slow down the rate of the chemical reaction which destroys food.
Food in the shape of big pieces has a surface area per volume which is small, so the heat takes a longer time to reach the inside of the food. So, to cook faster, the food needs to be cut into smaller pieces.
Sulphur is burnt in air to produce sulphur dioxide.
S(s) + O₂ → SO₂
Sulphur dioxide that is formed is mixed with excess oxygen and is conducted through the catalyst vanadium (V) oxide to raise the rate of reaction. A temperature of 500°C and a pressure of l to 2 atmospheres is used.
2SO₂(g) + O₂(g) → 2SO₃(g)
Sulphur trioxide that is formed is dissolved in concentrated sulphuric acid to form oleum at stage two.
SO₃ + H₂SO₄ → H₂S₂0₇
Sulphur trioxide does not dissolve directly in the water because this reaction releases too much heat and could even produce an explosion. Then,,, water is mixed with the oleum to produce concentrated sulphuric acid.
H₂S₂O₇ + H₂O (1) → 2 H₂SO₄( aq )