Would you please explain how to do this Chem problem?????

Question

How do you do problems with gases in reactions at STP?
Use molar volume to solve the following problems at STP:
a) the volume L occupied by 2.5 moles N2
b) the volume ml occupied by 0.420 mole He
c) the number of grams of neon contained in 11.2 L Neon gas
d) the number of moles of H2 in 1620 ml H2 gas

Note: 1 mole gas stp = 22.4 L
V1/n1=V2/n2

Answer 1

Well, for stiochometry problems, it all revolves around one basic thing, moles. when u get to moles, everything is accomplishable. Just remember that

Avogadro's Number = 6.02 X 10^23
Gas at STP will fill 22.4 L
Molar mass

think of stiocheomotry as a bridge in many ways,

First you have your known

Known

Then you have your unknown

Known----------------------- Unknown

Between there, you have moles of known

Known---------Known Moles----------Unkwn

And after known moles, you can get unkwn moles

Known-----Known moles-----Unknw moles-----Unkwn

So basically, get everything to moles, from there, its like ahh easy :)

But if that doesnt help, here are the answers

vol of N2 = (2.5 mol N2 ) (22.4L N2/ 1 mol N2) = 56 L

Vol of He in mL = (0.420 mol He) (22.4L He / 1 mol He) (1 mL He / 10^-3 L He) = 9408 mL He (sig Figs = 9.41 X 10^3 mL He)

Grams Ne = (11.2 L Ne) (1 mol Ne/ 22.4L Ne) (20.2g Ne/ 1 mol Ne) = 10.1 g Ne

Moles H2 = (1620 mL H2) (10^-3 L H2/ 1 mL H2 ) (1 mol H2 / 22.4L H2) = 0.072321 mol H2 (sig Fig= 7.233 X 10^-2 mol H2)

Answer 2

You equate the P, V, T conditions #1 to conditions #2 and crank out the answer exactly as you have shown. Then you use this equation in combo.

Pv=nrt. Where n number molecules, r is universal gas constant and t is absolute at standard temp of STP

Remember a mole of hydrogen is H2