Question

If you burnt 200 g of methane in 1000 g of air, what volume of carbon dioxide is produced if it was collected over water at 26 degrees C and the barometric pressure was 791 mm Hg

Answer 1

Mass of methane (CH_4) = 200 g Air used = 1000g moles of CH_4 = 200/(M.wt = 16) = 12.5 moles of air = 1000/(M wt-29) = 34.48 O_2 moles (21%) = 34.48 times 21/100 = 7.24 moles R times N CH_4 + 2 O_2 rightarrow CO_2 + 2 H_2 O implies from stoichiometric of reaction, n_c H_4: no_2: n_co_2 = 1: 2: 1-(A) implies 1 mole of CH_4 react with 2 mole of O_2 (2) to give 1 mole of C0_2 & 2 mole of H_2 O Therefore for 7.24 moles of O_2, n_CH_4 required: n_CH_4/no_2 = 1/2 implies n_CH_4/7.24 = 1/2 [n_CH_4 = 3.62 moles required] implies O_2 is limiting Reagent Therefore CO_2 produced: n_o_2/n_co_2 = 2 implies n_co_2 = 3.62 moles Now, using pv = n R T, volume = n R T/p implies (3.62) (0.0831) (299)/(791/760 atm) V_Co_2 = 86.42 L