A 20.0-L tank contains 4.86 * 10^-4 kg of helium at 18.0°C. The molar mass of helium is 4.00 g/mol. (a) How many moles of helium are in the tank?

Video transcript

everyone in this problem. We have a diver that uses scuba, oxygen cylinder of 12 liters filled with kg of di atomic oxygen gas. Okay, the molar mass of oxygen is 32 g per mole. And were asked how many moles of oxygen are present in the cylinder. Now, let's recall. We're talking about the number of moles. N Okay, this is equal to the mass M divided by the molar mass. Well, here we're given a mass of 16 kg. And so we have 16 kg. They were given a molar mass of 32 g per mole. Okay, so we have kilograms in the numerator. Are Mueller mass needs to be in terms of kilograms as well. So let's just work on the side here. Okay, big M is equal to 32 g per mole. Which is going to be 32 divided by kilograms per mole, divide by 1000 to go from grams to kilograms. We get 0.32 kilograms per mole. So we're going to divide by 0.032 kg Permal. The unit of kg will cancel when we divide. We're gonna be left with 500. Yeah. Okay, So we have 500 moles of oxygen. That's gonna be answer. D. That's it for this one. Thanks everyone for watching. See you in the next video.