Question

Pentane is burnt with 96000 cm3 of oxygen gas at room temperature and pressure.
Calculate the mass of zinc needed to react with 50 cm3 of 0.8 M of Hydrochloric acid.

Answer 1

96000 cm³ of oxygen is $\frac{96000}{1000\times22.4}=4.29$ mol of oxygen

The reaction between pentane and oxygen is:

C₅H₁₂ + 8O₂ = 5CO₂ + 6H₂O

50 cm³ of 0.8 M HCl contains $\frac{50\times0.8}{1000} = 0.04 \ mol$ of HCl

The equotion between Zn and HCl:

Zn + 2HCl = ZnCl₂ + H₂

The mass of zink needed is $\frac{0.04\times65.38}{2} = 1.3076$ g