Trimix is a gas mixture consisting of oxygen, helium, and nitrogen used for deep scuba dives. The helium is included to reduce the effects of nitrogen narcosis and oxygen toxicity that occur when too much nitrogen and oxygen dissolve in the blood. A tank of Trimix has a total pressure of 200 atm, and the partial pressure of He is 34 atm. What is the percent by volume of He in the tank? (LO 10.7) (a) 17% (b) 38% (c) 23% (d) 83%

Video transcript

Hi everyone. This problem reads. A gas mixture consisting of argon, carbon dioxide and helium is used for M. I. G. Welding. The total pressure of a tank of the gas mixture is 475 atmospheres and the partial pressure of argon is 309 atmospheres? What is the the percentage of argon in the tank by volume? So the question that we want to answer here is the percentage of argon in the tank by volume. So we need to calculate the partial pressure of argon or the part. Yes, we need to calculate the partial pressure of argon. And the way that we're going to do that is the partial pressure of a gas is equal to the mole fraction of that gas where mole fraction is represented by X times the total pressure. Okay, so in this case our gas is argon. Okay and we want to figure out the mole fraction. Okay, so this is what we're trying to solve for here, the mole fraction. So we need to isolate this variable. So we're gonna go ahead and divide both sides by the total pressure. So we get the mole fraction of the gas is equal to the pressure of the gas divided by the total pressure. Okay, so let's take a look at our problem to see what's given the pressure of the gas is atmospheres and our total pressure Is atmospheres. So we're given the two values that we need to solve this problem. So let's go ahead and plug those in. So we have 309 atmospheres divided by 475 atmospheres. This gives us 0.6505. The question asked for a percentage. So what we're going to do is we're going to take 0. and multiply it by 100% And we get 65.05%. So we can say that the percentage of argon in the tank by volume is going to be 65.1% argon and this is going to be our final answer. Okay, so that is it for this problem? I hope this was helpful.