Question

If 37.4 grams of water decomposes at 297 Kelvin and 1.30 atmospheres, how many liters of oxygen gas can be produced? Show all of the work used to solve this problem.

2 H2O (l) yields 2 H2 (g) + O2 (g)

Answer 1

Can you find the moles of water?

Answer 2

36 moles of water?

Answer 3

How did you get that?

Answer 4

Sorry i mean there are 2 moles of water

Answer 5

Yay, I get 2.1 moles but close enough.

Answer 6

Now can you find the moles of hydrogen?

Answer 7

Also 2?

Answer 8

Sweet.

Answer 9

But we are looking for info on oxygen. How many moles of oxygen do we have?

Answer 10

just one

Answer 11

Great. Now do you know the ideal gas law?

Answer 12

No.

Answer 13

PV=nRT

Answer 14

where P is pressure, V is volume, n is number of moles, R is a constant, and T is temp.

Answer 15

Ok so P=1.30 V=37.4 n=1 T=297?

Answer 16

Close. We are looking for V.

Answer 17

Actually V=X right

Answer 18

Yup, and we need to choose R in a way that cancels the appropriate units out.

Answer 19

Here is some helpful info http://mutuslab.cs.uwindsor.ca/schurko/introphyschem/handouts/gasconstant.pdf

Answer 20

We need R in the units we have: atm, mol, L, and K

Answer 21

And how do we get that?

Answer 22

Check out the link I posted.

Answer 23

I saw but im having trouble understanding

Answer 24

Would R=0.0821?

Answer 25

Yup, good! :)

Answer 26

Can you plug it all in and solve for V?

Answer 27

V=18.756?

Answer 28

That's what I get :)

Answer 29

Or 18.8L to three sig figs

Answer 30

Make sense?

Answer 31

Yes thank you

Answer 32

No worries. Happy studies!

Answer 33

can i ask you for a couple more?

Answer 34

Sure, but please open a new question. :) And if you are happy with the solution, give a medal. Thanks.

Answer 35

Yes of course thanks.