Question

. Copper(I) oxide, Cu2O, is reduced to metallic copper by heating in a stream of hydrogen gas. What mass of water is produced when 10.00 g copper is formed?

Answer 1

The mass of water is produced when 10.00 g copper is 0.07868 mol H₂O
Equation:Cu₂O +H₂ → 2Cu + H₂O

Get the mole ratios:1 mol Cu₂O : 1 mol H₂ : 2 mol Cu : 1 mol H₂O
number of moles = 0.1574 molSolve:
2mol Cu           0.1574 mol Cu--------------- =  ---------------------1 mol H₂O                   x
 x = 0.1574 mol Cu × 1 mol H₂O / 2mol Cu
= 0.07868 mol H₂O

Answer 2

Answer: 0.07868 mol H₂O

Explanation:

1) Chemical equation:

Cu₂O +H₂ → 2Cu + H₂O

2) mole ratios:

1 mol Cu₂O : 1 mol H₂ : 2 mol Cu : 1 mol H₂O

3) Convert 10.00 g of Cu to grams, using the atomic mass:

Atomic mass of Cu: 63.546 g/mol

number of moles = mass in grams / atomic mass = 10.00g / 63.546 g/mol

number of moles = 0.1574 mol

4) Use proportions

2mol Cu           0.1574 mol Cu
--------------- =  ---------------------
1 mol H₂O                   x

⇒ x = 0.1574 mol Cu × 1 mol H₂O / 2mol Cu = 0.07868 mol H₂O

That is the answer