Weight of copper oxide obtained, by heating 4.32 g of metallic copper with nitric acid and subsequent ignition, was 5.40 g. In another experiment, 2.30 g of copper oxide on reduction yielded 1.84 g of copper. Show that these findings are in accordance with the law of constant proportions.

Explanation

Experiment I
Weight of copper = 4.32 g
Weight of copper oxide = 5.40 gg
`therefore` Weight of oxygen = Weight of copper oxide - Weight of copper
= 5.40 - 4.32 = 1.08 g
Ratio of copper and oxygen,
`("Mass of copper")/("Mass of oxygen") = (4.32)/(1.08) = 4/1`
`therefore` Ratio is `4:1`
Experiment II
Weight of copper = 1.84 g Weight of copper oxide = 2.30 g
`therefore` Weight of oxygen = Weight of copper oxide - Weight of copper = 2.30 - 1.84 = 0.46 g
Ratio of copper and oxygen,
`("Mass of copper")/("Mass of oxygen") = (1.84)/(0.46) = 4/1`
`therefore` Ratio is `4:1`
As the ratio of copper and oxygen (by mass) is same in the two experiments, law of constant proportions is verified.