Natural gas is a mixture of hydrocarbons, primarily methane 1CH42 and ethane 1C2H62. A typical mixture might have Xmethane = 0.915 and Xethane = 0.085. Let's assume that we have a 15.50 g sample of natural gas in a volume of 15.00 L at a temperature of 20.00 °C. (a) How many total moles of gas are in the sample?

Video transcript

Hello everyone today. We have the following problem. A gas mixture contains propane. The mole fraction of propane being .7-1. And butane and the mole fraction of butane being .279. A sample of the mixture has a mass of 22.45 g and a volume of two liters at 25°C, calculate the total moles of gas in this mixture. So as you stated before, x is going to represent our small fraction, Essentially one mole of this mixture is going to contain .7-1 of propane and .279 moles of butane. And so what we want to do to find the average Mueller mass or the average m m is going to be taking our mole fractions and multiplying them by the molar mass. And so our mole fraction for propane is .7-1. And the molar mass of that is going to be 44.097 g per mole. And this is going to be using the masses from the periodic table and multiplying them by their respective atoms. And so we're gonna take that mole fraction, Multiply it by that molar mass for propane and do the same thing for butane. Butane has a mole fraction of .279 And its molar mass is 58.124 grams per mole. And this actually gives us 48.011 g of mixture per moles of mixture. And so lastly to find the moles per mixture. We are going to take our 22.45 g that was in the question stem of the mixture. This is the mass of our mixture. We're gonna multiply this by our new conversion factor that we have. That one mole mixture Or of the mixture is going to be equal to R 48.011 g of our mixture. Those units will cancel out, and we will ultimately be left with 0. moles of gas in this mixture. As our final answer with that, I hope this helped, and until next time.