Acids-Base Afterthoughts

Blog Post #6

Going into the test on thursday morning, I thought I knew what I was doing, I did all the practice problems, and I reviewed what I missed on the quiz, however when I was handed the test, I breezed through the first two pages, and then came face to face with something I blanked out on. I had no idea on what to do and how to set it up although I just did those problems less than 24 hours ago. 

After walking out of that classroom after handing in the test, I knew I could have done a lot better, but I tried on every problem to set it up the way I knew how to do it. So hopefully, it wont drop my grade too badly, and whenever I retake the aqueous solutions test, hopefully it will bring it back up. 

Current Status: Confused and Worried

Unknown Molar Mass Lab

Blog Post #5

I printed out the lab procedure for the final lab of the acids-base unit and almost had a slight panic attack. It said 'write your procedure here' and just gave you the materials you'd be using for the lab. However the procedure was the same as the 'Percent Acetic Acid' Lab, so it was fairly easy to then come up with the lab procedure. 

While actually going through with the lab, the unknown acid we had acquired would not dissolve just by swirling it in the distilled water, we then had to use hot plates. After almost what seemed like 20 minutes trying to get .4 grams of the unknown acid to break down we were finally able to then titrate our acid. After about three trials of our standardization of KHP and three trials of the unknown acid, we decided to then calculate what our percent error would be, that way we could tell if we were close or not. Colette and I were able to garner a .8% error which was far better than our acetic acid lab. 

Turns out, the unknown acid was the aspirin we had made earlier in the school year. 

Tedious Titration Lab

Blog Post #4

One of the three labs for this unit was a titration lab in which we had to find the percent acetic acid in vinegar. The procedure seemed fairly easy, and it was fairly easy to follow along with. However, when we figured out all our calculations we ended up with a 7% error. 

Trying to get all the titrations a light pink color was hard enough work as it was getting everything set up for the lab. What would have seemed as like an easy 30-40 minute lab, eventually turned into an almost 3 day lab-hence the title of the blog post. 

However though, we were able to get our percent error down after the 10 different titrations. 

Titrations

Blog Post #3

Earlier in the unit, we did a lesson over Titrations. Titration problems are fairly easy. You just need to know what goes where in a stoichiometry problem as that's how most of your chemistry titration problems are solved. 

EXAMPLE:

Determine the volume of 0.250 M KOH needed to titrate 25.0mL of 0.150 M HCl.

KOH + HCl --> H2O + KCl

.0250L HCl x .150mol HCl/1L x 1mol KOH/1mol HCL x 1L KOH/250mol KOH

1.50X10^-2

http://www.lakelandschools.org/webpages/lburris/imageGallery/graphics/Acid_Base/Titration.gif

Useful Links:

Titration Problems

Acid-Base Titration

pH and the Process of Equilibrium

Blog Post #2

When finding either pH, pOH, the concentration of H+ ions or OH- ions,

http://bclearningnetwork.com/LOR/media/calc12/unit4/U04L12/4boxdiag.gif

Equilibrium is a bit more challenging,in order to solve equilibrium equations, there's a method called the ICEbox method.
I=initial
C=change
E=equilibrium

http://scienceaid.co.uk/chemistry/physical/images/kaph.png

Helpful Links:
Bozeman Science Video
Crash Course
Crash Course #2

Acids/Bases

Blog Post #1

Last week, we started a new (difficult) unit over acids and bases. The difference between acids and bases are:
Acids: taste sour and feel sticky--pH<7 is corrosive
Bases: taste bitter and feel slippery--pH>7.1 is caustic

http://hungergames4chemistry.weebly.com/uploads/1/0/4/6/10462380/881963910.png?480

There are also two different main classifications of acids and bases:
Arrhenius Acids: produce hydrogen ions in a solution
Arrhenius Bases: produce hydroxide ions in a solution
Bronsted-Lowery Acids: donate a proton
Bronsted-Lowery Base: accept a proton

In the B.L acids/bases they produce conjugates which always come in pairs. 
CA: the substance formed when a proton is added to a base.
CB: the remaining substance when a proton is lost from an acid. 

Helpful Links:
Acids and Bases are Everywhere
CHEMTUTOR ACIDS AND BASES
Bozeman Science Video