Assume that a single cylinder of an automobile engine has a volume of 524 cm3. (a) If the cylinder is full of air at 74 C and 99.3 kPa, how many moles of O2 are present? (The mole fraction of O2 in dry air is 0.2095.) (b) How many grams of C8H18 could be combusted by this quantity of O2, assuming complete combustion with formation of CO2 and H2O?

Video transcript

Hey everyone. So here we have a pressure 1.21 atmosphere In a temperature of 325 Kelvin. They were as calculating mass of water that is needed to obtain 2.7 liters of oxygen gas. Htoo liquid And this yields H two. Yes plus O. Two. Yes. We have hydrogen auction on both sides. We have two hydrogen over here. One auction over here. 200 over here to auction over here. Does he have one option on the right side and two on the product side? Most of our two over here. Get to And put a two in front of H 20. We have four hydrogen over here. So if you put it to our front age too, We have four hydrogen over here as well. Now this is balanced and now we need to use the ideal gas law to find the most of the oxygen gas. This is pee pee. It was N. R. T. Our pressure is 1.21 atmosphere. The volume Is 2.7 L. Really good for the number of moles. Our constant is 0.08-1 theater sounds atmosphere about about moles. I'm Calvin And our temperature is Calvin. I'll be plugging the virus. You're gonna get 1.21 atmosphere I'm 2.7 L. It was an From 0.08 21 Leaders house atmosphere. And what about moles kelvin? I'm staring to 25 Kelvin. This will give us 3.267. It was an times .6825. So we divide both sides, 26.68 - five. We're gonna get in, Which is 0.122 four balls of oxygen gas. So now we need to convert moles of oxygen gas to mass of water, 0.122 court moles of oxygen gas. And in one mold caution gas, We have two moles of water And in one mole of water, we have the Mueller mass. And just to Times 1. plus 15 .999. Just give us 18.015. Let's give us 4.41 g Of H 20. Thanks for watching my video and I hope it was helpful.