Copper (1) 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 of copper is formed?

             1.41 g of H₂O

Solution:
The equation for given reaction is as follow,

                              Cu₂O  +  H₂     →     2 Cu  +  H₂O

According to equation,

      127 g (2 mole) Cu is produced along with  =  18 g (1 mole) of H₂O
So,
                      10 g Cu produced will generate  =  X g of H₂O

Solving for X,
                     X  =  (18 g × 10 g) ÷ 127 g

                     X  =  1.41 g of H₂O

"electrical energy" transforms to "thermal energy".hope my answer has you : )