[phann]

3.25x10^24 molecules of oxygen gas at STP are in a container. What volume of oxygen gas is present in the container?

Need sig figs as well

[Arkcon]

Please trouble yourself to read this forum's rules:  http://www.chemicalforums.com/index.php?topic=65859.0

We like to see some effort from a student, we don't just dump completed answers.  Asking us to do that is a bit unkind, demanding further that we give you the correct answer of the finest quality -- that is, don't get the sig figs wrong in your free answer, is spectacularly insulting.

[phann]

Ok, well, I tried dividing by Avagadro's number and then multiplying by 22.4L (because STP). From my understanding it flows as Convert to moles --> then liters? I feel like this should be the solution, yet it was marked wrong. I put 121 L as my final answer. Perhaps I messed up in significant figures.

I looked at this link http://abetterchemtext.com/Moles/mol_L_gas.htm


I see a lot Chemistry help on other sites where the answers are not in significant figures. I am simply trying to state that I wish for the answers to be in that form. There is no need to take it personally, that was not my clear intention.



edit: but i apologize for not putting my attempt in first

[Borek]

121 L looks OK to me (both in terms of the result and the sigfigs).

Note that STP is ambiguous.

[phann]

My teacher told us to use 22.4L, I guess that's where I got that from. Anyways I am puzzled on why it was marked wrong then. My thought process is correct right?



Also, a small question I have.

Are sig figs from calculation to calculation or do you apply the rules after the entire problem has been worked out?

[Arkcon]

Its best to round to significant figures at the last step.  If you have trouble carrying all the digits along, just carry one or two more than you will need at the very end.

[phann]

Alright, thank you