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Module 4 Q2

Posted: Wed Jan 15, 2020 1:21 am
by Jasmine 2C
State whether the equilibrium shifts towards products, reactants, or neither when the given change occurs.
2 HI(g) + Cl2(g) ⇌ 2 HCl(g) + I2(s) delta H° = -238.0 kJ.mol-1
i. The volume of the system is compressed.
ii. The temperature of the system is decreased.

For part i, using the quick way, we know that equilibrium shifts to the right because there are more moles of gas on the left. What is an explanation for the shift that doesn't count the moles on each side?

Re: Module 4 Q2

Posted: Wed Jan 15, 2020 8:02 am
by Justin Sarquiz 2F
concentration= n/V
K=[HCl]^2/ [Cl2][HI]^2
If the volume decreases, then the concentration increases. If you plug in values for the concentration, you will see that the Q is actually less than K. Since Q<K, the reaction proceeds to the right. He did a similar example in class where he plugged in values to prove that Q is less than K.

Re: Module 4 Q2

Posted: Wed Jan 15, 2020 8:46 pm
by 805303639
As Justin explained, compression affects the reaction by increasing the concentrations of gaseous reactants and products. The decrease in volume serves to multiply all concentrations by some factor. Since all concentrations increase by the same factor, the side with more moles experiences a greater relative increase in concentrations. The reaction proceeds in the opposite direction so as to minimize the effect of that increase.