Question

1g of a metal which has specific heat of 0.064 cal/g combines with oxygen to form 1.08g of oxide .what is the mass of M?

Answer 1

Answer : The mass of M is, 7.4 u

Explanation : Given,

Mass of oxide = 1.08 g

Mass of metal = 1 g

Mass oxygen = Mass of oxide - Mass of metal = 1.08 - 1 = 0.08 g

First we have to calculate the equivalent mass of metal.

$\text{Equivalent mass of metal}=\frac{\text{Mass of metal}\times 8}{\text{Mass of oxygen in oxide}}=\frac{1\times 8}{0.08}=100$

Now we have to calculate the approx, atomic mass of metal.

By Dulong petit's law,

$\text{Approx. Atomic mass of metal}\times \text{Specific heat}=6.4$

$\text{Approx. Atomic mass of metal}\times 0.064=6.4$

$\text{Approx. Atomic mass of metal}=100$

Now we have to calculate the valency of metal.

$\text{Valency of metal}=\frac{\text{Approx. Atomic mass of metal}}{\text{Equivalent mass of metal}}=\frac{100}{100}=1$

Now to correct the atomic mass of metal.

$\text{Corrected atomic mass of metal}=\text{Equivalent mass}\times \text{Valency}=7.4\times 1=7.4u$

Therefore, the mass of M is, 7.4 u