Dena A. answered • 08/03/15
Tutor
4.9
(136)
Former Chemistry Department Head with 10+ Years of Tutoring Experience
Sorry but your questions are cut off. Can you check the original question and re-post? In general, what you are dealing with is Le Chatelier's principle. Whenever a system is at equilibrium, the concentrations tend to stay constant. The question is "which of the following occurs when a few BLANK (that's where it's cut off on my computer)" should end in either the addition or subtraction of a certain species in the equation.
Note what happens when you add the lead II nitrate. The REACTANT CrO4-2 winds up precipitating (meaning it becomes solid and is no longer calculated in equilibrium concentrations). What they're telling you is that they REMOVED reactant. So here are your rules:
- If reactant is ADDED, equilibrium shifts to the RIGHT (favors products)
- If reactant is REMOVED, equilibrium shifts to the LEFT (favors reactants)
There appears, to me, to be only one answer above that hints that the reactants are now favored. Look at it; think about it. Let me know what you get and if you need any more help!
Dena A.
I'm curious as to where you're bringing the H+ into the picture from. This is the biggest mistake students make when dealing with these types of problems. Keep your eye on the prize. All the Le Chatelier principle states is that whenever a change is imposed on a system, it will resist that change. So work these problems out in four mental steps:
1. What was the change imposed on the system (i.e. was something removed or added, and was it a reactant or product?) Use only the word REACTANT or PRODUCT here; we don't care which species technically as long as it's aqueous.
2. What will the system do to counter this change?
3. How will it do it?
4. What will equilibrium favor?
Let me know what you guess about those questions and see if it helps.
Report
08/04/15
Mathalina S.
08/03/15