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.

Thurs 4/14/11

I. a.) Picked up Tritaion problems worksheet b.) Went over number 3: -H2SO4 + 2NAOH ---> 2H2O + NA2SO4 -How many ml of 0.6 M H2SO4 are needed to neutralize 90 ml of 0.4 M NAOH? (MA x VA = MB VB) ---> 2 X 6M x VA = 0.4M x 90 ml II. a.) Went over more examples of the same types of questions from #3: -HCL + CA(OH)2 would be MA x VA = 2MB x VB -H3PO4 + NAOH would be 3MA x VA = MB x VB -H2CO3 + AL(OH)3 would be 2MA x VA = 3MB x VB III. a.) Watched a CSI episode for the rest of class discussing a case where a man got pushed into a pool of highly concentrated acid and then burned, boiled, and died within a period of minutes. We discussed how the investigators would need vinegar (a base) to neutralize the acid before being able to pull the man out of the pool, otherwise they would burn too. If they just used water, it would slowly lower the concetration of the acid, but never actually neutralize it. Mr. Tucker also made his point that the most important part of the episode was that the wild boar was in season and that was why we were watching this in chemistry class.

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

Acids and Bases

Hello Everyone! Happy Tuesday!

So we did a few things in class today, most of which have to deal with the things we have been doing in class (Titration and Titration labs).

1. We went over the homework from last night (Monday) which was the Titration lab #2. Many people may have finished in class, but those of you that didn't had to finish it for homework. If you were absent, make sure you get Mr. Tucker to stamp it in for you. Here are some of the answers we got when going over the lab:

The Molarity of the Base for: Trial 1 is .89 M

Trial 2 is .87 M

Trial 3 is .87 M

Trial 4 is .63 M

Trial 5 is .94 M

1. The known substance is the Molarity Acid (.4 M) and the unknown is the Molarity of the base.

2. You could make the argument that both trial 4 and 5 are deviant trials because they are not so similar to the original three. You could just as easily make the argument that they are close enough, and that they are not deviant trials.

3. (Molarity of base at top)

4. a) .84

b) Again, this depends on which side you argued if you said 4 and 5 were deviants, your average is approximately .877 or .88. If you said they were not deviants, it stays the same at .84M

5. Yes, you should throw out the deviant trials, but you should be sure to mention them in your report so that you do not make that mistake again, and just so you remember there was one or multiple with data that was far off.

2. We went over the beginning of Titration lab 3

3. We went back to our tables in our lab groups, put our safety goggles on, and began our labs.

Basically what we did was we did the same thing we had been doing, but with solid acid opposed to liquid acid, and measuring how much base was needed to turn a set amount of acid pink.

***Homework***

Finish lab questions and anything else you might not have finished in class

Other things to take note of:

Someone took Mr. Tucker's keys, and if you know anything about them, he would appreciate it very much if you let him know.

Also, If you want to sign up for the "Chemistry Challenge" there are still teams that are needed. So, if you want to participate in this, and get a 20/20 for a lab grade, feel free to sign up.

Mr. Tucker has been assuring us that it will be somewhere on the scale of ok to fun, so if you like this kind of thing, sign up!

Hope this is helpful!

Solubitity

Things we did today:

1) Assigned Blog assignments for this week

2) Checked in the homework (Titration Lab 1)

3) Went back to labs groups and did another

trial for the Titration lab

Formula: Moles of Acid (.40M) x Drops of Acid (10 drop) = Moles of base (Unknown) x Drops of NaOH

4) Gave us Titration Lab Two

5) Homework: finish lab and do post lab questions

Thursday, April 7th 2011- Emma N.

At the beginning of class, we picked up 4 note sheets to put in our journal titled "ACIDS/BASES" and we also went into our lab groups and each separately read a paragraph from our text book paper copies, and had to write the "GIST" (hence the title) of the section we read. Including writing key words we read, and writing a 20 word summary of what we read including the key words we had previously written. We shared our summaries with each other, while Mr. Tucker checked in our Venn Diagrams we had for homework about the difference between acids and bases, and then shared our summaries with the class.

Then we took some notes.

1. Acids

A. What are some properties of acids?

-tastes sour

-reacts w/ metal to create H2 (g)

-turn litmus paper red

-react w/ carbonates to create CO2 (g)

*** IMPORTANT -creates H+ in water

-pH UNDER 7

B. What happens when acids dissociate in water?

HCl--> H+ + Cl-

HNO3 --> H+ + NO3-

2. Bases

A. What are some properties of bases?

-tastes bitter

-turns litmus paper blue

-turns pht (phenolphthalein) pink

*** IMPORTANT -creates OH- in water

-pH ABOVE 7

B. What happens when bases dissociate in wateR?

NaOH--> Na+ + OH-

NH3--> Na4+ + OH- (trick one!!)

3. WEAK AND STRONG ACIDS AND BASES

-Strong acids& bases completely dissociate in water (split apart)

-Weak acids&bases only partially separate in water.

At the end of class Mr. Tucker handed us a notecard which we wrote A on one side and B on the other, and he asked us questions and we had to decided which it was A, for acid, or B, for Base.

We received no additional additional homework except to finish the lab reports on moodle which are due tomorrow (Friday, April 8th, 2011)