# How many grams of copper oxide is formed if 100 grams of copper is taken for the combustion reaction?

Let’s write down given: m (copper) = 100 g. Copper interacted with oxygen.

Find: m (copper (II) oxide) -?

Solution:

Let us write the equation for the reaction of copper combustion.

Cu + O2 = CuO

Let’s arrange the coefficients.

2Cu + O2 = 2CuO

Calculate the molar mass of copper and copper (II) oxide

M (Cu) = 64 g / mol

M (CuO) = 64 + 16 = 80 g / mol

Since copper entered 2 mol, it is necessary to multiply the molar mass by the number of moles, we get 2 mol * 64 g / mol = 128 g

Since copper (II) oxide formed 2 mol, it is necessary to multiply the molar mass by the number of moles, we get 2 mol * 80 g / mol = 160 g

Let’s compose and solve the proportion.

Over copper (II) oxide we write x g, and under copper (II) oxide – 160 g

Over the copper we write 100 g, and under the copper – 128 g

x = 100 * 160/128 = 125 g

Answer: m (CuO) = 125 g