JEE MAIN - Chemistry (2023 - 13th April Evening Shift - No. 16)
$$1 \mathrm{~g}$$ of a carbonate $$\left(\mathrm{M}_{2} \mathrm{CO}_{3}\right)$$ on treatment with excess $$\mathrm{HCl}$$ produces $$0.01 \mathrm{~mol}$$ of $$\mathrm{CO}_{2}$$. The molar mass of $$\mathrm{M}_{2} \mathrm{CO}_{3}$$ is __________ $$\mathrm{g} ~\mathrm{mol}^{-1}$$. (Nearest integer)
Answer
100
Explanation
When the carbonate reacts with HCl, it produces CO2, as shown in the following balanced equation:
$$\mathrm{M}_2\mathrm{CO}_3 + 2\mathrm{HCl} \rightarrow 2\mathrm{MCl} + \mathrm{H}_2\mathrm{O} + \mathrm{CO}_2$$
From the problem, we know that 1 g of the carbonate produces 0.01 mol of CO2.
To determine the molar mass of the carbonate, we can use the stoichiometry of the reaction:
1 mol of $$\mathrm{M}_2\mathrm{CO}_3$$ produces 1 mol of CO2.
So, 0.01 mol of CO2 corresponds to 0.01 mol of $$\mathrm{M}_2\mathrm{CO}_3$$.
Now, we can find the molar mass of $$\mathrm{M}_2\mathrm{CO}_3$$:
$$\frac{\text{mass of }\mathrm{M}_2\mathrm{CO}_3}{\text{moles of }\mathrm{M}_2\mathrm{CO}_3} = \text{molar mass of }\mathrm{M}_2\mathrm{CO}_3$$
$$\frac{1 \text{ g}}{0.01 \text{ mol}} = 100 \text{ g mol}^{-1}$$
So, the molar mass of $$\mathrm{M}_2\mathrm{CO}_3$$ is approximately 100 g/mol.
$$\mathrm{M}_2\mathrm{CO}_3 + 2\mathrm{HCl} \rightarrow 2\mathrm{MCl} + \mathrm{H}_2\mathrm{O} + \mathrm{CO}_2$$
From the problem, we know that 1 g of the carbonate produces 0.01 mol of CO2.
To determine the molar mass of the carbonate, we can use the stoichiometry of the reaction:
1 mol of $$\mathrm{M}_2\mathrm{CO}_3$$ produces 1 mol of CO2.
So, 0.01 mol of CO2 corresponds to 0.01 mol of $$\mathrm{M}_2\mathrm{CO}_3$$.
Now, we can find the molar mass of $$\mathrm{M}_2\mathrm{CO}_3$$:
$$\frac{\text{mass of }\mathrm{M}_2\mathrm{CO}_3}{\text{moles of }\mathrm{M}_2\mathrm{CO}_3} = \text{molar mass of }\mathrm{M}_2\mathrm{CO}_3$$
$$\frac{1 \text{ g}}{0.01 \text{ mol}} = 100 \text{ g mol}^{-1}$$
So, the molar mass of $$\mathrm{M}_2\mathrm{CO}_3$$ is approximately 100 g/mol.
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