Question

For the equation 2 HCI + Zn ⇒ H₂ +ZnCI₂ suppose you had 2.00 g HCI and enough Zn.

a. What mass, in grams, would you have of Zn?

b. How many grams of H₂ would be produced?

Please show your work!!

Answer 1

Zinc weighs 65.38 grams per mole, so we’ve got 0.994 moles of zinc (I’ll worry about sig figs at the end). HCl weighs 36.46 grams per mile, so we’ve got 1.78 moles of HCl. However, two moles of HCl react with one mole of zinc. So only 1.78/2 = 0.890 moles of Zinc are going to react.

One mole of zinc produces one mole of hydrogen, which weigh 2.02 grams per mole. So 0.890 moles * 2.02 grams/mole means 1.90 grams of hydrogen will be produced.

Since we have 2 sig figs in the weights given, the answer should have 2 sig figs, thus 1.9 grams.

This is just an example