## HW 11.67 Reasoning

Drishti_Jain_1D
Posts: 22
Joined: Fri Jul 22, 2016 3:00 am

### HW 11.67 Reasoning

2HCl --> H2 + Cl2
Pressures in order of HCl, H2, and Cl2 are 2.0, 1.0, 3.0. Why do you have to push the reaction as far to the left as possible? And how do you do this? Why can't you first find Q and use that to determine which eay the reaction moves when using ICE?

Karan Ishii 3E
Posts: 21
Joined: Wed Sep 21, 2016 3:00 pm

### Re: HW 11.67 Reasoning

The reaction system favors the reverse reaction because the K value is very very low. I don't think this is due to the pressure of the system because initially there is the same pressure on both sides of the reaction so I don't think this would result in a favoring of a side (correct me if I'm wrong).

You're right where you can first find the Q which would be greater than the K, indicating that the reaction would proceed to favor the left.

Chem_Mod
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### Re: HW 11.67 Reasoning

Great answer Karan. The only thing I'll add is that we can make this assumption of pushing everything to left because of the low Ka value. Therefore, we push it left until one of the products reaches 0. Since there is only 1.0 bar (mol) of H2, we subtract 1.0 from H2 and O2 resulting in new initials of 1.0 and 2.0, respectively. We also add 2.0 mol to HCl (due to stoichiometry), result in a new initial of 4.0.