Asked by Savanna

Calculate the moles of CO2 formed when
4.2 mol of C3H8 react with 20.6 mol O2. Answer in units of mol.

So, the balanced equation is C3H8 + 5 O2
==> 3 CO2 + 4 H2O . I thought the answer would be 12.36 mol, but when I type it in it's wrong. Please help!
Answered by DrBob222
My best educated guess is that you are reporting the number with more significant figures than you are allowed. I obtained 12.36 also, however, you're allowed only 2 s.f. (from the 4.2) so the 12.35 rounds to 12.4 mols. Try that. If that doesn't fix the problem let me know at this post.
Answered by DrBob222
......so the 12.36 rounds to 12.4 mols.
Answered by Savanna
Thanks! The site actually asks for 5 s.f., and it's saying that I am wrong no matter what I am typing in... I will just have to ask my teacher about it tomorrow! Thanks again!
Answered by DrBob222
If you have posted the problem exactly as is then the 4.2 has two s.f. and the 20.6 has three s.f. and you will be allowed 2 in the answer. You would need 4.2000 and 20.600 to be able to use 5 s.f.
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