## "quick" way?

Clarice Chui 2C
Posts: 87
Joined: Fri Aug 30, 2019 12:16 am

### "quick" way?

What did Dr. Lavelle mean by the "quick way" of using Le Chatelier's Principle and what is the long way?

Aliya Jain 2B
Posts: 86
Joined: Wed Sep 11, 2019 12:16 am

### Re: "quick" way?

The quick way is just knowing that when pressure is increasing, then the reaction will go towards the direction with less moles and when the pressure is decreasing, the reaction will go towards the direction with more moles. The longer way is realizing that when pressure is changing, the actual volume changes, and so concentration changes. Both will lead to the right answer, however, the longer way provides the correct reasoning.

Manav Govil 1B
Posts: 89
Joined: Sat Sep 07, 2019 12:19 am

### Re: "quick" way?

The long way is comparing the K with the newly made Q that occurs after Le Chat occurs. We do this by calculating the equilibrium constant K and Q, see which one is greater, and decide whether the reaction shifta to the left or right.

The quick way is by simply looking at the reaction and counting the moles on both sides and see if the reaction shifts left or right. If there are more moles on the left side of the reaction, the reaction will shift right. If there are moles on the right side of the reaction, the reaction will shift left.

Sam McNeill 1E
Posts: 100
Joined: Sat Aug 24, 2019 12:17 am

### Re: "quick" way?

Lavelle clarified in class that the "quick way" would not actually give the correct reasoning to answer the question, so I would just know the long way since the quick way does not correctly give reasoning.

sarahforman_Dis2I
Posts: 98
Joined: Sat Aug 17, 2019 12:18 am

### Re: "quick" way?

Clarice Chui 2C wrote:What did Dr. Lavelle mean by the "quick way" of using Le Chatelier's Principle and what is the long way?

The "quick way" is remembering that if the volume decreases, the reaction will shift to the side that has the fewest moles of gas. If the volume increases, the reaction will shift to the side with more moles of gas. Although this is true, Dr. Lavelle wanted us to understand that it is not the change in pressure that causes the change, but the change in volume (which results in a change in concentration). A change in concentration will change K, so the reaction must shift.