Net # of moles of gas produced, module question  [ENDORSED]

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ellevialthea1C
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Net # of moles of gas produced, module question

Postby ellevialthea1C » Sun Jun 26, 2016 12:11 am

In the online module, the question asks:
During a summer camping weekend, 4 moles of butane (C4H10) gas were used for cooking. Choose the right balanced equation for the combustion of 4 moles of butane gas. What is the net number of moles of gas produced?

Now, it is my understanding that once you balance the equation properly, you take the Stoichiometric coefficient of the gas produced & that will be the net number of moles as asked for.

In the possible answers that follow, the choices were
A. 4 C4H10(g) + 26 O2(g) ----> 16 CO2(g) + 20 H2O(g) ; 6
B. 4 C4H10(g) + 26 O2(g) ----> 16 CO2(g) + 18 H2O(g) ; 4
C. 4 C4H10(g) + 25 O2(g) ----> 16 CO2(g) + 20 H2O(g) ; 6
D. 4 C4H10(g) + 26 O2(g) ----> 16 CO2(g) + 20 H2O(g) ; 5

After working it out on my own, I came to the conclusion that
4 C4H10(g) + 26 O2(g) ----> 16 CO2(g) + 20 H2O(g) was the balanced equation, but I did not find a net number of moles in the answer choices that coincided with this (even after simplifying the coefficients). What is the correct answer choice? Am I going about how to solve this completely wrong?

Chem_Mod
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Re: Net # of moles of gas produced, module question  [ENDORSED]

Postby Chem_Mod » Sun Jun 26, 2016 1:40 pm

the problem asks for the net production of gas, since all the reactants and products are in gas phase, the net should be the sum of coefficient of the product - the sum of coefficient of the reactants. so 36-30=6

Aprice_1J
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Joined: Wed Sep 18, 2019 12:16 am

Re: Net # of moles of gas produced, module question

Postby Aprice_1J » Mon Sep 30, 2019 10:26 pm

For this problem (During a summer camping weekend 4 moles of butane (C4H10) gas were used for cooking. Chose the right balanced equation for the combustion of 4 moles of butane gas. What is the net number of moles of gas produced?) which is located in the balancing chemical equations post-module, I know that if something is burning in the presence of oxygen oxidation occurs and therefore CO2 and H2O are released but how do you know if the oxygen is present? Is this something that you infer? Otherwise wouldn't carbon monoxide be released?

Justin Seok 2A
Posts: 104
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Re: Net # of moles of gas produced, module question

Postby Justin Seok 2A » Mon Sep 30, 2019 11:39 pm

I think that the word "combustion" in the problem allows you to infer the presence of oxygen gas in the equation. And with carbon monoxide, it is formed during incomplete combustion when there is not enough oxygen to form carbon dioxide, but I would guess that for simpler problems where incomplete combustion or a specific amount of oxygen aren't given, you can assume that there is an abundance of oxygen gas.


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