Answer Key

3) (4 pts) Consider the combustion of octane (C 8 H 18 ):C 8 H 18 (l) + 12 O 2 (g) 8CO 2 (g) + 9 H 2 O (g)If oxygen is consumed at the rate of 6.5 atm/h, at what rate CO 2 and H 2 O would be produced?(Report your answer in proper unit and correct number of sig figs)[Hint: write expressions for relative rates]Δ[C H ]Rate = − 8 18 1= −Δt12Δ[O 2] 1=Δt8Δ[CO 2]Δt= 91Δ[H 2O]ΔtGiven that −Δ[O 2]= 6.5 atm/hΔtFrom the above rate expression, we know that− 121Δ[O 2] 1=Δt8Δ[CO 2]Δt= 91Δ[H 2O]ΔtTherefore,Δ[CO 2]Δt= 128Δ[O 2]Δt= 128 × 6.5 atm/h = 4.3 atm/handΔ[H 2O]Δt= 129Δ[O 2]Δt= 129 × 6.5 atm/h = 4.9 atm/hPlease note that the rate is always expressed as a positive number by convention.