Notes in class

We have been going over Aqueous solutions during class, and this week we went over chemical reactions. We then started talking about using molarity with the stoichiometry that we have already learned.
Here is the flowchart that we completed in class to go through all the steps in the process:

The practice problems we did in class were not difficult at all, instead they were nearly identical to what we had done before. The first problem was a limiting reagent problem in which we had to add an extra step to help convert for the molarity of the solutions. First to find the mass we had to use the moles of the solute over total volume of the solution (solute and solvent together) to be able to find the moles in the reactants. Then we did conversions we were familiar with to convert to grams by using normal mole to mole ratio and molar masses. Then we knew whichever created the smaller mass was the limiting reagent, just like previous problems we have worked with. 

And here is the chart nearly identical to what is in our book, and this is what Mrs. Frankenberg showed us to help solve for the next steps in solving problems like this.

http://img.docstoccdn.com/thumb/orig/641889.png

Here are some links to help with these types of problems:
http://misterguch.brinkster.net/PRA048.pdf
http://www.chemcollective.org/activities/tutorials/stoich/solution_stoi
http://www.eiu.edu/eiuchem/genchem/tutorial4.pdf

Molarity Lab day 2

On the second day of the lab, there wasn't much of the procedure to be done. The solid from the solution had sat overnight and dried in the filter paper that we used. All we had to do was use the same balance as we did in day one to weigh the mass of the product made. With the two masses, we were able to subtract to then find the difference. Then, we worked backward in a molarity problem to find the molarity of the silver nitrate that was at the crime scene. We converted the mass that we had found to grams, used the mol to mol ratio, and divided by 0.01L, which was the amount of the unknown solution that we used. In the end, we came to the conclusion that Mr. Green was our suspect because the molarity we calculated fit within the range of his description. Finally, we had to make a lab report with our partner over the entire lab.
Here are some links to help with the calculations that we did in our lab:
http://chemistry.about.com/od/examplechemistrycalculations/a/How-To-Calculate-Molarity-Of-A-Solution.htm
http://www.chemteam.info/Solutions/Molarity.html

Molarity Lab day 1

Today in class, we conducted the molarity lab This was somewhat set up like the game Clue, with various suspects with different weapons, from which we have to determine who killed Miss Scarlett. From the background information, we have two available test solutions, NaCl and Na2CO3, and two different possible murder weapons, AgNO3, and KI.
First we had to set up four double replacement reactions to figure out how the possible murderous solutions would react with the known solutions provided. With this, we found that both reactions with KI created two aqueous products, otherwise would not precipitate, and therefore these KI cannot be the murder weapon. In our experiment today, we combined 10mL of the unknown solution with 25mL of Na2CO3. This turned into a white fluid that looked like milk, but when looking closely, we could see that there was crystallization occurring. Next, we took filter paper, weighed it on the balance, and placed it in a funnel over a beaker. The crystals then collected in filter paper when the fluid drained out and this was left in class overnight to dry.
Here are some pictures from our experiment:

Dilutions lab

Since we have been learning about how to calculate the Molarity and Liters in a dilution, we did a lab to go along with it at the end of class. To start, we had a small sup full of 9mL of water, and to this we added 1mL of blue food dye. Next we took the pipette and removed 1mL of the mixture and put it in the next cup. Then, to this cup, we added another 9mL of water, and the food dye became slightly lighter. We continued this pattern of 1mL from the previous cup and 9mL of water until the cup was clear, and there was no more dye to be seen. After doing this, we did some dilution calculations to see the concentration in each cup.
here is how to do this math: http://www.quansysbio.com/dilutions
https://www.youtube.com/watch?v=v6dnEp58mVk

These are all the cups, from most concentrated to least from our experiment.