Chemistry Labs

Problem 1

An amount of 23 g of a gas (density ρ=2.05\rho = 2.05 g dm−3^{-3} at STP) when burned gives 44 g of carbon dioxide and 27 g of water. What is the structural formula of the gas (compound)?
Step 2 of 3: Elemental counts from products
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n(COX2)=1 mol⇒n(C)=1 mol;n(HX2O)=1.5 mol⇒n(H)=3 moln(\ce{CO2}) = 1\ \text{mol} \Rightarrow n(\text{C}) = 1\ \text{mol}; \quad n(\ce{H2O}) = 1.5\ \text{mol} \Rightarrow n(\text{H}) = 3\ \text{mol}
Analysis

44 g CO2 contain 1 mol of C (12 g); 27 g H2O contain 3 mol of H (3 g). Together only 15 g < 23 g, so the compound also holds oxygen: m(O)=8m(\text{O}) = 8 g, i.e. 0.5 mol.