5J 5: increase in pressure

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Siddiq 1E
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Joined: Fri Aug 09, 2019 12:15 am

5J 5: increase in pressure

Postby Siddiq 1E » Tue Jan 21, 2020 1:33 pm

So I understand the basic set up of the question, but I am confused on the answer for D. To me it seems like there's more moles on the left side so the reaction would favor the products?? I'm also confused about B :(

Esha Chawla 2E
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Joined: Thu Jul 25, 2019 12:17 am

Re: 5J 5: increase in pressure

Postby Esha Chawla 2E » Tue Jan 21, 2020 1:51 pm

Siddiq 1E wrote:So I understand the basic set up of the question, but I am confused on the answer for D. To me it seems like there's more moles on the left side so the reaction would favor the products?? I'm also confused about B :(


For Part D, you have to take the stoichiometric coefficients into account. Thus, on the left side there are 2 moles of gas, because there is a "2" in front of HD(g). Similarly, on the right side of the equation, there is 1 mole of H2 (g) because there is an implied "1" in front of H2(g) AND there is 1 mole of D2 (g) because there is an implied "1" in front of D2 (g). Thus, there are also 2 moles of gas on the right side of the equation. Thus, if there is an increase in pressure (by decreasing volume), neither side of the reaction will be favored, as both sides of the reaction have 2 moles of gas.

Hui Qiao Wu 1I
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Re: 5J 5: increase in pressure

Postby Hui Qiao Wu 1I » Wed Jan 22, 2020 3:37 pm

For B): First, you would not take solids into consideration when adding up the coefficients on each side. H2O has one mole on the reactants side. H2 and CO each have 1 mole on the products side; together, it's two moles. Since pressure increases, the volume decreases, meaning it will favor the side with fewer gas molecules. Therefore, it will favor the reactants side.

AniP_2D
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Re: 5J 5: increase in pressure

Postby AniP_2D » Wed Jan 22, 2020 4:08 pm

For part B, you do not take C into account since it is a solid so technically the left side would have 1 mol and the right side would have 2 mols, hence the reason why the system would shift to the left. For D, the amount of moles on both sides equals 2, so since the amount of moles are equal, there would be no change.

Simon Dionson 4I
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Re: 5J 5: increase in pressure

Postby Simon Dionson 4I » Thu Jan 23, 2020 1:13 pm

Increasing pressure will favor the side with fewer mols of gas

B) 1mol of H2O vs 1mol of H2 + 1mol CO --> reactants favored
D) 2mol of HD vs 1 mol of H2 + 1mol of D2 --> neither favored since both have 2 mols of gases


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