Question

What is the weight of the residue obtained when $2.76g$ of silver carbonate is strongly heated?

• A. $2.16g$
• B. $2.46g$
• C. $2.32g$
• D. $2.64g$

Answer 1

The correct option is A

$2.16g$

The explanation of the correct option:

C)$\mathbf{2}\mathbf{.}\mathbf{16}\mathit{g}$

Step 1:Write the chemical equation.

• The reaction of heating of ${\mathrm{Ag}}_2{\mathrm{CO}}_3$(Silver carbonate) gives rise to elemental silver with the liberation of carbon dioxide and oxygen gases.

${\mathrm{Ag}}_2{\mathrm{CO}}_3\left(\mathrm{s}\right)\to \mathrm{Ag}\left(\mathrm{s}\right)+{\mathrm{CO}}_2\left(\mathrm{g}\right)+\frac{1}{2}{\mathrm{O}}_2\left(\mathrm{g}\right)$

Step 2: Calculate the molecular formulae.

• Atomic masses are given as:$\mathrm{Ag}=108\mathrm{u}$; $\mathrm{O}=16\mathrm{u};\mathrm{C}=12\mathrm{u}$
• ${\mathrm{Ag}}_2{\mathrm{CO}}_3$ : $(108\times 2)+12+(16\times 3)=276g$
• $2{\mathrm{Ag}}_{}$: $108\times 2=216g$

Step 3: Calculation

• By applying the cross multiplication method-

Now, $276g$ of ${\mathrm{Ag}}_2{\mathrm{CO}}_3$giving out $216g$the silver residue

so, for $2.76g$of ${\mathrm{Ag}}_2{\mathrm{CO}}_3$ it will provide - $\frac{2.76\times 216}{276}=2.16g$ of $\mathrm{Ag}$

• Therefore, a residue of $2.16g$ silver is obtained on heating $2.76g$of Silver carbonate.

Hence option C) $\mathbf{2}\mathbf{.}\mathbf{16}\mathit{g}$ is the correct answer.