# 0.310 mol of reacts with 0.810 mol of oxygen. How many moles of water are produced

 hacienda Posts: 5, Reputation: 10 Junior Member #2 Sep 9, 2010, 09:35 AM
0.310 mol of reacts with 0.810 mol of oxygen. How much octane is left?
 DrBob1 Posts: 425, Reputation: 445 Full Member #3 Sep 9, 2010, 09:53 AM
You need to post the balanced equation; we will check it for you.

The equation will tell how much octane is consumed by 0.810 moles of O2. The difference is the moles or grams of residual octane.

Post your work and we will check it for you.
 DrBob1 Posts: 425, Reputation: 445 Full Member #4 Sep 9, 2010, 09:57 AM
You need to post the balanced equation; we will check it for you.

The equation tells how many moles of water is produced from the 0.810 moles of O2.

Post your results and we will check that too.
hacienda (Sep 9, 2010 10:14 AM):   Source:
 hacienda Posts: 5, Reputation: 10 Junior Member #5 Sep 9, 2010, 10:13 AM
Comment on DrBob1's post
Quote:
 Originally Posted by DrBob1 You need to post the balanced equation; we will check it for you. The equation tells how many moles of water is produced from the 0.810 moles of O2. Post your results and we will check that too.
Balanced Equation C8H18(g) + O2(g) ? CO2(g) + H2O(g). 2 C8H18(g) + 25 O2(g) = 16 CO2(g) + 18 H2O(g)
 hacienda Posts: 5, Reputation: 10 Junior Member #6 Sep 9, 2010, 10:15 AM
Comment on DrBob1's post
Quote:
 Originally Posted by DrBob1 You need to post the balanced equation; we will check it for you. The equation will tell how much octane is consumed by 0.810 moles of O2. The difference is the moles or grams of residual octane. Post your work and we will check it for you.
c8h18(g) + o2(g) ? co2(g) + h2o(g). 2 c8h18(g) + 25 o2(g) = 16 co2(g) + 18 h2o(g)
 Unknown008 Posts: 8,147, Reputation: 3745 Uber Member #7 Sep 9, 2010, 11:57 AM
Ok, so, 2 moles of C8H18 consumes 25 moles of oxygen gas.

So, 1 mole of octane consumes (25/2) = 12.5 moles of oxygen gas.
Or 1 mole of oxygen burns (2/25) = 0.08 moles of octane

And,

0.310 moles of octane consume (12.5x0.310) = 3.875 moles of oxygen gas.

Or

0.810 moles of oxygen gas burns (0.08x0.810) = 0.0648 moles of octane.

How much octane is left can be easily found now
 Unknown008 Posts: 8,147, Reputation: 3745 Uber Member #8 Sep 9, 2010, 12:00 PM
From what I told you to do in my previous post, try working the amount of moles of water out now
 DrBob1 Posts: 425, Reputation: 445 Full Member #9 Sep 10, 2010, 11:56 AM
Maybe this is a trick question: there is such a small amount of oxygen that I wonder if it will burn at all!?

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