Question

On heating 632 kg of Cu in air, 7.92 kg of copper oxide is formed. Another sample of copper oxide

contains 80% of copper. From these data, show that the law of definite proportion is valid.​

Answer 1

Answer : For a given data, the law of definite proportion is valid.​

Explanation : Given,

Mass of Cu = 6.32 Kg

Mass of CuO = 7.92 Kg

Law of definite proportion : It states that the given compound always contains its component elements in a fixed ratio (by mass).

First we have to calculate the percent composition of Cu.

Formula used :

$\%\text{ composition of Cu}=\frac{\text{Mass of Cu}}{\text{Mass of CuO}}\times 100$

Now put all the given values in this formula, we get :

$\%\text{ composition of Cu}=\frac{6.32Kg}{7.92Kg}\times 100=79.79\%\approx 80\%$

As we are given that the percentage of copper in another sample is, 80 % and the theoretical percentage of copper is also equal to 80 %.

So, from this we conclude that the law of definite proportion is valid for this problem.