Prep for Quest

By: Katie Coy

Overview:
Hello all who were 'absent' (aka on an AP Euro field trip) today! We started off class today by talking about the homework question that was assigned last night. It was actually not a common ion problem, rather it was a solution stoichiometry problem from earlier in the year. We did not go over how to solve this problem in class and you will not have to know how to solve this problem on the Quest tomorrow. Speaking of the quiz... we do have a Quest on LeChatelier's Principle that TOMORROW! Ms. Friedmann is going to post a VIDEO that goes through all that we reviewed (we did not learn anything new) today. I currently do not see the video posted, but do not fret, Ms. Friedmann said she will post it as soon as it uploads. Keep checking the unit 9 box on the Moodle page for the video on today's lesson. If you do not want to watch the video, I will post a quick summary of all that we learned today... hope it is helpful. :)

What is going to be on the Quest:

1. LeChatelier's Principle- qualitative questions such as "If more CO is added to this equation, will it shift to the right or to the left?"   
2. Ksp common ion problems
3. Ksp problems
1. Calculate the concentrations of substances at equilibrium
2. Calculate Ksp using solubility- these can be found in the packet that we did, questions 8 a,b,c, and d.

Number two is what we went over today, since Ms. Friedmann felt that we could benefit from more information on common ion problems.

Common Ion Problems:

These are the problems in which we are dissolving a substance into something other than pure water. We went over an example problem that is explained in the video, so I will just talk about the steps that we took to solve the problem. 

Example one: What is the solubility of PbCl2 in 0.100 M MgCl2? The Ksp of PbCl2 is 1.7(10^-5). As one can see, the solubility (aka x) is what you should be solving for. Again, if you would like and explanation of this please visit the wonderful video Ms. Friedmann is going to post.

Solubility and Ksp Problems:

Another thing that we reviewed today was the formulas that we learned yesterday. Those formulas are:

# of ions produced:

2                                                  the square root of Ksp

3                                                  the cube root of Ksp/4

4                                                  the fourth root of Ksp/ 27 

These are used to figure out the solubility of equations without using the ICE tables. YOU SHOULD MEMORIZE these equations for tomorrow's quiz. Anyways, you may be wondering when we use these formulas. Well, when you are given a question that reads, 'Which of the following has the lowest solubility?' use the equations. Here are the notes that we took in class. Again, if you are confused on this topic, please consult Ms. Friedmann's video.

Homework:

1. Study for the Quest!

One other important thing, Ms. Friedmann wanted to tell everyone that she apologizes for not giving the usual homework so that we could prepare for the quest. With her busy life outside of school, it has been very hard for her to assign homework and to post items (like keys) on Moodle. She thanks all of us for being very patient. 

Good luck studying and the next blogger is.... Georgia.