midterm 6 b

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midterm 6 b

Postby WGaines_2E » Mon Mar 09, 2020 10:04 pm

For which process will dH and dG be expected to be the most similar?

a)2Al(s) + Fe2O3(s) -> 2Fe(s) +2Al2O3(s)
b) 2Na(s) + 2H2O(l) -> 2NaOH(aq) + H2(g)
c) 2NO2(g) -> N2O4(g)
d) 2H2(g) + O2(g) -> 2H2O(g)

Kylie Lim 4G
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Re: midterm 6 b

Postby Kylie Lim 4G » Mon Mar 09, 2020 10:28 pm

A, because the reaction has the smallest deltaS values, meaning in the equation deltaG = deltaH - TdeltaS, change in gibbs and change in enthalpy will be the closest to each other

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Re: midterm 6 b

Postby anjali41 » Mon Mar 09, 2020 10:30 pm

The states of matter hint at the answer, as all the products and reactants in answer choice a are solids.

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Re: midterm 6 b

Postby CynthiaLy4F » Tue Mar 10, 2020 9:41 am

For this problem, the answer would be the reaction that has the smallest change in entropy, which in this case is A.

John Liang 2I
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Re: midterm 6 b

Postby John Liang 2I » Tue Mar 10, 2020 10:44 am

since dG=dH-TdS, you want to find the smallest dS value. we see this in the first choice because the solid states remain most solid. hope this helps

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Re: midterm 6 b

Postby AniP_2D » Tue Mar 10, 2020 3:12 pm

For deltaH and deltaG to be very similar, the change in entropy has to be minimal, so you would look to see which reaction has the least change in entropy, which would be A since the phase remains a solid throughout the reaction.

Rida Ismail 2E
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Re: midterm 6 b

Postby Rida Ismail 2E » Tue Mar 10, 2020 3:51 pm

In order to solve this problem, you need to see which choice gives you an answer that has the smallest delta S. A would be the answer because that is the only one in which the state stays solid throughout, and solids have the lowest entropy values.

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