Zinc metal reacts with hydrochloric acid to form zinc chloride and hydrogen gas.

Question

a.) Write a balanced reaction

b.) How many moles of HCI are consumed per 0.4 mole of zinc?

C.) What volume of hydrogen gas is produced at standard temperature and pressure per 2.5 g of zinc used?

Answer 1

(a) Zn_(s) + 2HCl_(aq) = ZnCl_2(aq) + H_2(g)

(b) 0.8 moles

We can see above that the mole ratio of zinc to hydrochloric acid is 1:2 , that is, 1 mole of zinc reacts with 2 moles of HCl. Hence, for 0.4 moles of Zn, the amount of HCl will be 2X0.4=0.8 moles

(c) molar volume at standard temperature and pressure=22.4 L

moles= mass/molar mass moles=volume/molar volume (in case of gases)

For 2.5 g of Zn used, moles of zinc= 2.5/65.4 = 0.038 moles

molar ratio of Zn to H₂ is 1:1

so moles of hydrogen gas produced= 0.038 moles

volume of hydrogen gas produced= 0.038 X 22.4 = 0.856 L