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Net Number of Moles

Posted: Tue Oct 02, 2018 12:05 pm
What's the best way to find the net number of moles produced in a chemical reaction?
Ex. 4 moles of butane (C4H10) gas were combusted. Find the net number of moles of gas produced.
Ex. was taken from pre-module.

Re: Net Number of Moles

Posted: Tue Oct 02, 2018 12:24 pm
I believe you'd just write out the complete chemical equation and the do total number of moles final - total number of moles initial to find out the net number of moles.
Also, when writing out the combustion remember that the other reactant is oxygen and the products are CO2 and H20
Hope this helped!

Re: Net Number of Moles

Posted: Tue Oct 02, 2018 12:32 pm
The previous reply is correct. For that question, the net number of moles is 4 because you add up the moles on the left side of the equation (reactants) and then subtract that from the total number of moles on the right side of the equations (products). Follow up question: If there is a net gain then net moles will always be positive, if there is a net loss then the net moles will always be negative?

Re: Net Number of Moles

Posted: Wed Oct 03, 2018 1:10 pm
After balancing the equation, you get 4C4H10 + 26O2 -> 16CO2 + 20H20. To calculate the net number of moles of gas produced in this question, you just have to remember this simple formula:
The sum of the coefficients of the product - sum of the coefficients of reactants

So for this question, it would be 36[16+20]-30[4+26]=6
Therefore, the net number of moles of gas would be 6.

Hope this helped!