Question

a reaction of 12.640 g of copper oxide with 0.316 g hydrogen produces 2.844 g of water and x g of copper. x = ___ g

Explanation:

Step1: Apply law of conservation of mass

The law of conservation of mass states that the total mass of reactants is equal to the total mass of products in a chemical reaction. The reactants are copper oxide and hydrogen, and the products are water and copper. So, mass of reactants = mass of products.
The mass of reactants is $12.640 + 0.316$ g. The mass of products is $2.844+X$ g.

Step2: Set up the equation

$12.640 + 0.316=2.844 + X$

Step3: Solve for X

$X=(12.640 + 0.316)-2.844$
$X = 12.956-2.844$
$X=10.112$ g

Answer:

$10.112$