Question

A 1.650g sample containing lithium hydrogen carbonate is decomposed with heat. If the mass loss is 0.255g, what is the percentage of LiHCO3 in the unknown mixture?

LiHCO3(s) ----------> LiCO3(s) + H2CO3(g)

Answer 1

Answer is :-

H2O and CO2 are lost (1 mol each per 2 mol LiHCO3)

1 mol H2O + 1 mol CO2 = 61.02 g

0.255 g / 61.02 g = 0.004179 mol each of H2O and CO2

Starterd with 2x0.004179 mol LiHCO3 = 0.008358 mol

0.008358 mol x 67.96 g/mol of LiHCO3 = 0.5680 gram

0.5680 g / 1.650 g = 0.3443 or 34.43%