1. Higher tier only

Potassium reacts with oxygen to produce potassium oxide.

4K + O₂ → 2K₂O

i) Calculate the maximum mass of potassium oxide that could be produced when 15.6 g of potassium reacts completely with oxygen.

[3]

A_r(K) = 39 A_r(O) = 16

Mass = .......................... g

ii) Another reaction requires 0.050 mol of oxygen gas. Calculate the number of molecules in 0.050 mol of oxygen gas. Give your answer in standard form.

[2]

Avogadro’s number = 6.0 × 10²³

Number of molecules = ...............................