28 friday

we went over questions 4,5 in the booklet
study guide going over on monday
went over titration questions.
Dave is the next scribe

Percent Dissociation

Tuesday, May 25th 2010

Today, we had a mini refresher, from what we learned on Friday. The Ka and Kb equations. We also, talked about the pH lab we did last Tuesday as well. To review some more, we did this interactive Naming the Acids sort of thing.

We went over questions 1-4 on Acid-Base Equilibria Worksheet 4.

We did example 8, on page 30 in the booklet. We also, learned a new topic in class. It was how to calculate the Percent Dissociation.

The formula to calculate Percent dissociation is

Percent dissociation = Concentration of Dissociation Species

---------------------------------------------------- x 100%

Original Concentration of Acid or Base

We also did examples 10 and 11, as practice. We were assigned to do Assignment 4 in the yellow booklet, the odd numbers. You could do the even questions as practice if you want.

*Grade 12 bbq tomorrow! Don't forget to bring sunscreen. =]

**Our chemistry exam is on Monday, June 21st 2010 in the afternoon! 27 more days till our exam.

Our next scribe is.....annab.

Next scribe will be Jocelyn!

Electrolyte/Nonelectrolyte

Friday, May 21, 2010, we read pages 19 to 29. We learned new terms like electrolyte and non
electrolyte. "conducts electricity" is an electrolyte and "do not
conduct electricity" is a non electrolyte. An example of a non
electrolyte is water (H2O). An example of an electrolyte is sodium
hydroxide (NaOH). Then, Ms. K showed us a demo that determine if a
compound is an electrolyte or non electrolyte. We looked at questions
on page 22. Questions 4, 9, 10 and 14 are identified as non
electrolytes. We added 2 questions #13. H2O and #14. NaCl. Electrolytes
are question #s 1,2,3,5,6,7,8,11,12,13,14.
*all organic compounds are NON electrolytes*
*strong acids are ALWAYS strong electrolytes*
*strong acids are considered to completely dissociate in water*
We also did the 'calculating the dissociation constant' on page 29.
After the booklet, Ms. K assigned us to do Acid -Base Equilibria
Worksheet 4 questions #1-4.
Have a nice long weekend!!!

OOPS NEXT SCRIBE WILL BE JANINE :D !

Logs/Antilogs pH/pOH

Well we had a sub yesterday, but we were given 2 sheets to work on about logs/antilogs related to pH and pOH. There were a couple of formulas in the sheet that we could remember in order to find pH and pOH.

pH = - log[H⁺] pOH = - log [OH^-]
pH + pOH = 14.0 [H⁺][OH^-] = 1.0 x 10^-14
[H+] = anitlog (-pH) = 10^-pH [OH^-] = antilog (-pOH) =10^ -pOH

Today, we went over the worksheet #2 about acids and bases #’s 1 and 2 where we were to identify which one is an acid, base, conjugate acid and conjugate base. Also, to determine whether they were Arrhenius acids/bases or Bronsted-Lowry acids/bases. We also did the Kw problems #’s 1-10 and the Acid-Base Assignment #6 numbers 1 and 2 on the board today.

Mrs. K assigned numbers 3 and 4 today and this was to be handed at the end of the class.

Dont forget the equilibrium law can be written as:

Kw = [H_3O⁺][OH^-] Where the value of Kw is constant at 1.0 x 10^-14.

Conjugate Acids and Conjugate Bases

Friday may 14, 2010

We went over the booklet Acid & Bases pg 3- 12. Then we were given a worsheet to work on the first page - Acids & Bases Project Assignment I, indentify the acid, base, conjugate acid(ca), & conjugate base(cb).
Answers:
1.a) acid + base <---> ca + cb
b) acid + base <---> ca + cb
c) base + acid <---> ca + cb
d) base + acid <---> ca + cb
e) acid + base <---> cb + ca

2. write the equation for the reaction of each of the following with water.Indicate wether the ion or molecule is an acid and base. Which one of these are arrhenius acid/bases and which are Bronsted-Lowry acids/bases?
e.g. HBr + H2O <--->H3O+ + Br- , Bronsted - Lowry & Arrhenius Acid
Answers:
2. a) <--->C3H3O2- + H3O+ Arrhenius Acid & Bronsted - Lowry
b) <--->HS- + OH- Bronsted - Lowry Base
c) <--->HSe+ + OH- Bronsted - Lowry Base
d) <---> H2CO3 + OH- Arrhenius Acid & Bronsted - Lowry

Homework for this weekend:
- finish the Next page of the woorksheet Acids & Bases Woorksheet 2 Question 1 & 2, hand in for monday.
- also the foldables (Arrhenius, Bronsted - Lowry , Lewis) follow the rubric for foldables to get a perfect mark this is also hand in for monday.

& the next scribe will be: julien:)

Foldables

So today in chem, we made foldables about the different types of models. Such as the Lewis, Arrhenion and the Bronsted Lowry Model. This assignment will be due Monday. Don't forget to be creative with this and add every little bit of detail to each model.
And our next scribe will be bernadette.

hi there guyss! On monday, we corrected the work sheet called "solubility equilibria assignment #3. And also, we looked at pages 36-37. We learned how to determine if a solution is saturated or unsaturated.

Remember guyyys!:
- Q-Ksp, the solution is just saturated and no ppt( no precipitation)
-Q> Kso, the solution is saturated and a ppt occurs.
- Q< Ksp, the solution is unsaturated and no ppt formed.

GOODLUCK ON THE TESST' DUN DUNN DUUUUUNNN......
the scribe for thursday will be arjel:)

May 07, Friday

I wasn't late today, so I volunteered to do the blog. :) :)


First, we did the questions 3 & 4 in the Solubility Equilibria Assignment #1. Obtain the answers from Ms. K. Note: in letters b and d you have to change the unit to moles/liter before you can solve for the Ksp.


We also went over the pages 31-35 on the Chemical Equilibrium booklet. In that, we learned a new lesson, determining ion concentration from Ksp. For all of you who hates ICE, you'll life will be easier. It's no different from the ICE method we've been doing, except that:

• the initial concentration of the ions (products), before dissolving, is zero.

• reaction is consists of a saturated solution as reactants and ions as products so you get to IGNORE the saturated solution, the solid one, in your ice table.

Example: The Ksp of magnesium hydroxide is 8.9 x 10 ⁻12. Determine the solubility of Mg(OH)₂.

• Mg(OH)₂(s) <=> Mg2+ (aq) + 2OH⁻(aq)

I...............___.................0................0
C.............___................+x................+2x
E..............___...............+x................+2x


To solve for x, use the formula, Ksp = [products] and substitute the values. We'll find that the solubility of Mg(OH)₂ is 1.3 x 10-4.


That's determining ion concentration using Ksp in PURE WATER. Another thing we learned is determining ion concentration with an ION IN COMMON WITH THE COMPOUND.

Example: The Ksp of magnesium hydroxide is 8.9 x 10 ⁻12. What is the solubility of magnesium hydroxide in a 0.10 M solution of NaOH.

Step 1: Determine the concentration of the common ion, OH ⁻.

NaOH(s) <=> Na+(aq) + OH -(aq)
[OH⁻] = [NaOH] = 0.10 M

Step 2: Set up an ICE table for Mg(OH )₂.

• Mg(OH)₂(s) <=> Mg2+ (aq) + 2OH⁻(aq)

I...............___.................0................0
C.............___................+x................+2x
E..............___...............+x................0.10 +2x

***You have to include the concentration of OH - from NaOH(s) in the table because when we dissolve Mg(OH)₂ in the solution, OH ions are present. According to Le Chatelier's Principle, adding more OH ions to a saturated solution would increase the overall concentration of the products shifting the equilibrium to the left. This would result in more solid formed and a decrease solubility.***


Step 3: Substitute values into the solubility product expression.

Ksp = [Mg2+][OH-]2

8.9 x 10⁻12= (x)(0.10 + 2x)2

**at this point, you can see that you'll have a quadratic equation if you solve further, so, ignore the x of the ion in common, OH. Ms. K said that it's too tiny to matter.**

8.9 x 10⁻12= (x)(0.10)2

8.9 x 10⁻12= 0.01x

8.9 x 10⁻10M = x

Let's check if the value makes sense. The solubility of Mg(OH)₂ in pure water is 1.3 x 10-4 M and in a 0.10 solution of NaOH is 8.9 x 10⁻10M. The solubility decreased, just as we predicted.



I dont know if I have to pick for someone to do the next scribe... if so, i'll pick Ericka! :) :)

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May 4 AND 5

SOOO pretty much what we did on May 4 is go over the study guide questions which Ms. Kozoriz already put up the answers to. We studied the rest of the period because test was on MAY 5th!

I really don't know what else to put... and I feel like I should scribe for May 6 since this post is quite short and sad.

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