Suppose you have two 1-L flasks, one containing N2 at STP,
the o...

Question

Suppose you have two 1-L flasks, one containing N2 at STP, 
the other containing CH4 at STP. How do these systems compare 
with respect to (b) density?

Accepted Answer

hey everyone in this example, we need to compare the density of chlorine gas and krypton at standard temperature and pressure. If both gasses are in separate two liter flasks. So because the prompt mentioned density, we wanted to call that our symbol for density is our rose symbol and that's going to be equal to our mass divided by volume. Now, because we're dealing with gasses, we want to also recall our formula for the ideal gas equation. What you recall is the pressure times volume equal to our most of our gas times, the gas constant, R times temperature, which we can also reinterpret as pressure times volume equal to the mass of our gas times, the gas constant R times temperature and divided by the molar mass of our gas. And in terms of density, we would write this equation out so that we have rent row or density equal to our pressure, multiplied by the molar mass of our gas and then divided by the gas constant R. Times temperature. And as you can see in our equation that we have determined below our value for density is directly proportional to our molar mass of our gasses because they're both in the numerator of our equation here. And we would recognize that because they have this direct relationship, we would assume that as our molar mass of our gas increases in value, therefore our density of that gas will also increase. So to compare our gasses for this question, we're going to look up our molar mass for chlorine gas from our periodic tables, which we will see is equal to a value of 70.90 g per mole. We're going to do the same thing for our Krypton gas, which from our periodic table we would see has a molar mass of 83. g per mole. And so what we can conclude based on these molar masses is that our density of our krypton gas is going to be greater than the density of our chlorine gas. And that is due to the fact that we recognize the direct relationship between density and molar mass, and we see that krypton has the higher molar mass and therefore will have the higher density. And so this will be our final answer to complete this example. So I hope that everything I explained was clear. If you have any questions, please leave them down below and I will see everyone in the next practice video.

Suppose you have two 1-L flasks, one containing N2 at STP, the other containing CH4 at STP. How do these systems compare with respect to (b) density?

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