Pleae help! calculate the mass of .45 mol of argon gas.

Please show me how you got the answer, so I know how to apply it to the rest of my questions.

thank you

You need to set up a conversation factor label problem. It's a little hard to do on the computer, but I will try my best to show how this is done.

You're trying to find the mass (g) of argon, Ar.

? g Ar = (0.45 mol Ar * 39.95 g Ar) / 1 mol Ar = 18 g Ar (with significant figures) or 17.9775 g Ar (without significant figures)

You have to start with the number of moles you are given times the molar mass of the substance to get the mass of your sample. The reason I showed dividing by one is to illustrate how the unit mol Ar cancels out and that you are left with the unit g Ar, which is what the question asked for.

I hope this helps!

Use conversion unit of 1mol/molar mass g or molar mass/ 1 mol to solve. This is a one step problem. First step write down what you are given .45 mol Ar. Next decide what its asking for......mass? Yes, then we know mass is in grams just like our conversion formula mentioned previosly. The mass should be on top so we will use molar mass/ 1 mol. Next you have to find molar mass of Ar. 39.948 g (biggest number in square with Ar) so here is the setup

(.45 mol Ar) (39.948g /1 mol) = you can solve it 😄. Cancel out your units mol on top and mol on bottom- left with grams as unit. Good luck in Chem b/c this is the tip of the iceberg, they only get harder from here. This is a must to learn to get the rest of chem stoichiometry, solubility, gas laws, and pretty much everything.

mass Ar = (0.45 mol Ar) * (39.948 grams Ar / 1 mol Ar) = 17.98 grams Ar