A 2.10 g mixture of NaHCO3 and KClO3 requires 100 mL of 0.1NHCl for complete reaction. Calculate the amount of residue (as nearest integer) that would be obtained on strongly heating 2.20 g of the same mixture.
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Solution
Only NaHCO3 reacts with 0.1NHCl.
Let x g be the weight of NaHCO3 and (2.1−x) g be the weight of KClO3. Milliequivalents of NaHCO3=100×0.1=10 Weight of NaHCO3=10×10−3×84=0.84g Weight of KClO3=2.1−0.84=1.26g 2NaHCO3Δ→Na2CO3+H2O↑+CO2↑ 2 mol of NaHCO3=2×82 g Na2CO3=106 g 2KClO3Δ→2KCl+3O2↑ The residue will have Na2CO3 and KCl. KClO3=122.5 g KCl=74.5 g Weight of residue from 2.1 g of mixture=5384×0.84+74.5122.5×1.26=0.53+0.766=1.296 g Weight of residue from 2.2 g of the mixture =0.84+1.26=2.20 g=1.2962.1×2.2=1.358 g