numerical on law of multiple proportion

Question

Copper gives two oxides , on heating 1.0gm of each in hydrogen gas, 0.888gm and 0.799gm of the metals are produced . Show that the results agree with the law of multiple proportion.

Answer 1

The law of multiple proportions states that when two elements (like Cu and O) combine with each other to form more than one compound, the weights of one element that combine with a fixed weight of the other are in a ratio of small whole numbers.

 

In the compound that yields 0.888 g of Cu, the remainder of the 1 g must by O, so that would be 0.112 g O.  The parts of Cu that combine with 1 part of O =0.888/0.112 =  7.93

 

In the compound that yields 0.799 g of Cu, the remainder of the 1 g must be O, so that would be 0.201 g.  The parts of Cu that combine with 1 part of O = 0.799/0.201 = 3.98.

 

The ratio of Cu that combines with a fixed mass of O is 7.93:3.98 or 2:1. So the compounds would be CuO and Cu₂O