In an experiment, 4.90 g of copper oxide was obtained from 3.92 g of copper. In another experiment, 4.55 g of copper oxide gave, on reduction, 3.64 g of copper. Show with the help of calculations that these figures verify the law of constant proportions.
The law of constant proportion is also known as the law of definite proportion. This law states that in a compound, the elements are always present in definite proportions by mass. The reaction between copper and oxygen leading to the formation of copper oxide is written as follows
2Cu + O2 → 2CuO
As per the given data, 4.90 g of copper oxide was obtained from 3.92 g of copper. Therefore, the percentage of copper in 4.90g of CuO will be
= (mass of copper / mass of CuO) X 100
= (3.92 / 4.9) X 100
= 80 %
As per the data of the second experiment, 3.64g of copper is obtained from 4.55g of CuO. So, percentage of copper in this sample of copper oxide will be
= (mass of copper / mass of CuO) X 100
= (3.64 / 4.55) X 100
= 80 %
Thus, we see that percentage of copper in both samples of CuO is the same. This means that copper and oxygen always combine in a fixed ratio by mass to form CuO. Thus the law of constant proportions is satisfied here.
The law of constant proportion is also known as the law of definite proportion. This law states that in a compound, the elements are always present in definite proportions by mass. The reaction between copper and oxygen leading to the formation of copper oxide is written as follows
2Cu + O2 → 2CuO
As per the given data, 4.90 g of copper oxide was obtained from 3.92 g of copper. Therefore, the percentage of copper in 4.90g of CuO will be
= (mass of copper / mass of CuO) X 100
= (3.92 / 4.9) X 100
= 80 %
As per the data of the second experiment, 3.64g of copper is obtained from 4.55g of CuO. So, percentage of copper in this sample of copper oxide will be
= (mass of copper / mass of CuO) X 100
= (3.64 / 4.55) X 100
= 80 %
Thus, we see that percentage of copper in both samples of CuO is the same. This means that copper and oxygen always combine in a fixed ratio by mass to form CuO. Thus the law of constant proportions is satisfied here.
