Question

Find the amount of residue obtained in grams when $2.76\text{g}$ of silver carbonate is strongly heated.
(Molar mass of $Ag=108\text{g/mol}$)
$A{g}_{2}C{O}_3\stackrel{\Delta }{\to }2Ag+C{O}_2+\frac{1}{2}{O}_2$

• A. $2.16\text{g}$
• B. $2.48\text{g}$
• C. $2.32\text{g}$
• D. $2.64\text{g}$

Answer 1

The correct option is A $2.16\text{g}$

$A{g}_{2}C{O}_3\stackrel{heat}{\to }2Ag+C{O}_2\uparrow +\frac{1}{2}{O}_2\uparrow$ Number of moles of $A{g}_{2}C{O}_3=\frac{\text{given mass}}{\text{molar mass}}=\frac{2.76}{276}=0.01\text{mol}$

According to stoichiometry,
1 mol of $A{g}_{2}C{O}_3$ decomposes to produce 2 mol of $Ag$
0.01 mol of $A{g}_{2}C{O}_3$ decomposes to produce $\frac{2}{1}\times 0.01=0.02$ mol of $Ag$
Mass of 0.02 mol of $Ag=0.02\times 108=2.16\text{g}$ of $Ag$