Q.

How many grams of residue is obtained by heating 2.76 g of silver carbonate

(Given: Molar mass of C, O and Ag are 12, 16 and 108 g mol-1 respectively)              [2026]

1 1.08 g  
2 2.16 g  
3 3.24 g  
4 4.32 g  

Ans.

(2)

Molar mass of silver carbonate (Ag2CO3)

=(2×108+12+3×16) g mol-1=276 g mol-1

Moles of silver carbonate (nAg2CO3)

=Mass of Ag2CO3Molar mass of Ag2CO3

=(2.76276) mol=0.01 mol

Ag2CO3→Δ2Ag+12O2+CO2

As per reaction stoichiometry:

Moles of Ag=2×moles of Ag2CO3

Moles of Ag=2×0.01 mol=0.02 mol

Mass of Ag=moles of Ag×molar mass of Ag

                       =0.02×108 g=2.16 g