Answer:
159.1 grams
Step-by-step explanation:
You need the balanced chemical equation for the reaction between copper and copper II oxide:
Cu + CuO → 2 CuO
From the equation, you see that 1 mole of copper reacts with 1 mole of copper II oxide to produce 2 moles of copper II oxide. You can use this information to set up a proportion:
1 mole Cu / 1 mole CuO = 2 moles CuO / x moles CuO
Solving for x, you get:
x = 2 moles CuO
Now you can use the molar mass of copper II oxide to convert moles to grams:
2 moles CuO x 79.55 g/mol = 159.1 g CuO
Therefore, 159.1 grams of copper II oxide will be formed when 125 grams of copper reacts.