Sapling (5/6) #18

Jessica Luong 3K · Postby **Jessica Luong 3K** » Sun Mar 07, 2021 11:41 am

For #18, I have to find the equilibrium constant K using the deltaG(f) equation. I followed all of the instructions where you find the deltaG and then use the equation deltaG = -RT*ln(K). However, I keep getting the wrong answer. Can someone help me with the steps to solve this problem?

Adalia 3E · Postby **Adalia 3E** » Sun Mar 07, 2021 11:47 am

One thing that stumped me was that I kept forgetting to convert from kJ to J when calculating for the equilibrium constant. Maybe that could be a place where you miscalculated?

Peter DePaul 1E · Postby **Peter DePaul 1E** » Sun Mar 07, 2021 12:00 pm

So for reaction 1 $C_{2}H_{2}(g) + 2H_{2}(g)\rightleftharpoons C_{2}H_{6}(g)$
$\Delta G = \sum G(Products)-\sum G(Reactants)$
$\Delta G = (-32.82 kJ/mol) - (209.2 kJ/mol) = -242.0 kJ/mol = -2.420\times 10^{5} J/mol$
After that you substitute into the equation $\Delta G = -RTln(k)$ so we now solve for K
$K = e^{\frac{\Delta G}{-RT}}$ so $K = e^{\frac{-2.420\times 10^{5} J/mol}{-8.314J\cdot K^{-1}\cdot mol^{-1}(298.15 K) = 2.5\times 10^{42}$

Follow the same process for the other reaction

Natalie Do 3F · Postby **Natalie Do 3F** » Sun Mar 07, 2021 7:49 pm

1. Find G (convert from joules to moles)
ΔG∘r=ΣnΔG∘f(products)−ΣnΔG∘f(reactants)
2. Find K from G
ΔG∘r=−RTln(K)

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Sapling (5/6) #18

Sapling (5/6) #18

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