Question

Our good friend and pseudo scientist, homer simpson, attempts to analyze 300 mg of an unknown compound containing only c and h by burning it in excess oxygen. 540 mg of h2o is produced. you may assume that all the hydrogen in the compound ended up as water.

Answer 1

$C_{x}H_{y} + O_{2} --\ \textgreater \ x CO_{2} + \frac{y}{2} H{2}O 540mg H_{2}O* \frac{1 mmol H_{2}O}{18 mg H_{2}O} =30 mmol H_{2}O \\ \\30 mmolH_{2}O -have - 60 mmol H \\ \\ 60 mmol H* \frac{1mg H}{1 mmol H} =60 mg H \\ \\300mg C_{x}H_{y} - 60 mg H= 240 mg C \\ \\ 240 mgC* \frac{1mmol}{12mg} =20 mmol C 20 mmol C: 60 mmol H=1 mol C : 3 mol H$