Resources

This post is simply for me to share some of the resources I have found that are helping me this unit!

• https://www.chem.purdue.edu/gchelp/howtosolveit/Equilibrium/Calculating_pHandpOH.htm

• http://www.chemteam.info/AcidBase/AcidBase.html

• http://www.chemteam.info/AcidBase/pH-Strong-Acid-Base.html

• http://www.chemteam.info/AcidBase/Strong-Weak-AcidBase.html

• http://www.sciencegeek.net/Chemistry/taters/Unit8pH.htm

• http://calculator.tutorvista.com/pH-calculator.html

Converting Using the Ph Grid

Using this grid. you can easily see how we convert from H to OH, OH to pOH, pOH to H, and so on!

Don't know why we do all of this? Well, I'll explain.

When converting from pH to pOH you simply use the equation pOH + pH= 14. This is because the pH scale is 14 and the amount of hydroxide ions you have will always be counterbalanced by the amount of hydronium ions to equal 14.

We convert between H and OH with the natural ionization rate of water over the H or OH concentration to find the amount needed.

The H concentration is 10^-pH because moving up or down by an increment of 1 on the pH scale equals 10 times more acidic or basic of a solution. And that is measured by the H/OH concentration.

I hope those explanations helped you remember why we are using these equations!

Vitamin C Lab

So today in class we did the Vitamin C lab! We started out by making a 1.00 mg/ml standard solution of vitamin c by crushing a 500 mg tablet and adding 500 ml of water. We took 20 drops of that and added in 3 drops of startch, our indicator. We added startch into the reaction because when we add iodine, we'll know the reaction is done when the solution turns dark blue. That means there is no more vitamin C solution to react with. Anyways, after the 3 drops of startch we added drops of iodine into the solution until it turned (and stayed) a dark blue. We tested pear nectar, V8, apple juice, and white grapefruit juice. 

In the end, grapefruit juice had the highest vitamin c concentration and pear nectar had the lowest. 

Analysis of Commercial Hydrogen Peroxide

This lab involves combining molarity and stoichiometry to determine the percent of commercial hydrogen peroxide, This is produced when you react peroxide with potassium permanganate.

First we allocated solutions of KMnO4 and H2O2 and measured their masses.

Then, we added 20-25 drops of H2O2 to a test tube, plus 4 drops of sulfuric acid.

Then we added KMnO4 until a faint pink color remained.

Once we did this, we calculated the percent of hydrogen peroxide through stoichiometry and molarity problems.

Molarity Lab

The second lab we are doing this quarter is about a murder mystery! It is kind of a play off on the game Clue, and our job is to figure out what mystery chemical was used to murder Ms. Scarlet.

First we set up double replacement reactions to see which substances had the likelihood of producing a clear liquid (as seen on the scene of the crime).

Then, we went back in lab and ran an experiment with NaCO3 and the mystery substance to see what precipitate it produced. We collected it in filter paper and are waiting for it to dry!

Once we collect the dried substance on Tuesday we can then determine the molarity of the substance and identify the murderer. 

Edit-- the murderer is Mr. Green because the molarity of AgNO3 is .06. 

Quiz

Today in class we took a quiz over the first part of chapter 15 and some review over stoichiometry and limiting reagents. Overall, I thought the quiz was pretty okay (even though that's what I thought for the last 3 tests and we all know how that went).

So far in Chapter 15, we have learned about dilution, molarity, hydrogen bonding, and saturated, unsaturated, and supersaturated solutions. I am really curious to see how these all tie together in the second half of the chapter.

If anyone struggled with the quiz or was looking for more practice for the real test, here are some helpful links I used to study for today's test.

https://app.schoology.com/course/309537052/materials/gp/455085153

http://www.chemteam.info/Solutions/Dilution.html

http://www.chemteam.info/Solutions/Molarity.html

**Overall,, I find the chemteam.info website really helpful.

Dilution lab

Today in class we did a dilution lab! We started with a stock solution containing 20 drops of red food coloring and took equal portions of that stock, added 9 mL of water to each aliquot, and put that new substance in a new cup. We kept doing this until the liquid was clear. 

Overall, this lab was really helpful in learning how to solve real life dilution problems!

Here are some links if you need more help with dilution:

http://www.docbrown.info/page04/4_73calcs14other3.htm
http://chemistry.about.com/od/chemistryquickreview/a/dilutionmath.htm
http://chemistry.about.com/od/chemistryquickreview/a/dilutionmath.htm