Friday 4/15/11

Friday during class we picked up pages 2-6 of the pH tutorial. We worked on pages 2, 3 and 4. These pages were all about how to tell the pH of something if you know the given [H+] and vice versa. In part one we learned how to predict the pH. If you have 1x10^-5 the predicted pH would be 5 and it would be an acid. If it was 1x10^-12 than the pH would be twelve and it would be a base. Part two we learned the inverse of it. If the given pH is 2 than the predicted [H+] would be 1x10^-2 and it would be a base. In part three we learned how to find the ph if the number x 10^x is more than one. You use your calculator, hit (-), than (LOG) and than enter your number, and than (-) and the exponent. Part 4 we learned the inverse of that, you use (LOG), (-) and than the given pH. Then we learned how to find if something is Neutral, Basic or Acidic just by looking at the [H+] and the [OH-]. If the [H+] is greater than the [OH-] than it is an acid. The reverse works in the opposite manner, respectively. Lastly we learned how to determine the pH of something if we know the pOH and vice versa. Basically, the two numbers need to add up to 14, so you can figure it out.

Friday, 4/8/11, Acids and Bases

This is a late post.....Mon and Tue are below:

Acids and Bases, 4/8/11
1. Went over the properties of acids and bases.

2. Took a partner quiz on acids and bases.

3. Took notes.

NOTES:
Part 1- The Simulation
1. List the molecules and/or ions present in the solution of HCl.
-H+ Cl- H20
2.List the molecules and/or ions present in the solution of NaOH.
-Na+ OH- H2O
3. What is the purpose of the phenolphthalein (phth)?
-it is an indicator (base/ OH- turns pink)
4. Why doesnt the phenolphthalein change colors when it is first added to the cup?
-Acid + pht
NO OH-
5. What is the reaction that is happening when the NaOH is added to the cup?
-Neutralization reaction, NaOH + HCl produces NaCl + H2O
6. What has to be true for the phenolphthalein to turn pink?
- OH- > H+
first slight pink
EQUIVALENCE POINT
4. Part 2 of the notes: We did a lab using the base NaOH and the acid HCl. In the lab we had to put 10drops of HCl into a paper cup with one drop of phth. Next we add 1 drop of NaOH into the cup and mix it around when we see the pink. We continued this procedure until the pink remained the color of the mixture. Here is my groups data:


Drops HCl (.40M) Drops NaOH (X M)
Trial 1 10 36
Trial 2 10 31
Trial 3 10 67
Trial 4 10 63

We then used the equation Macid x Drops acid = Mbase x Drops base to figure out the molarity of NaOH in each trial. Here are our results:
Trial 1- .11 Trial 2- .13
Trial 3- .06 Trial 4- .06
The average concentration of the NaOH was .18.
In our lab results we had deviant trials. You can disguard deviant trials however mention it.

Posted by Therese Snow at 8:21 PM 0 comments
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Labels: Acids and Bases, Snow