Cooper (II) Chloride Lab

Day 1

To start the lab we took the mass of a baby food jar then added 4.00grams of Copper (II) Chloride to the jar and 50.0grams of distilled water. We stirred the solution until it was completely dissolved. After polishing off a nail with steel wool we placed it in the container and let it sit.

Day 2

We pulled of the remainder of the nail out of the jar. Then, we slowly poured out solution careful to not lose any copper product. We did the same two more times after washing it with HCl and more distilled water. We set the jar with copper out to dry. To finish off we took the ending mass of the nail.

Day 3

We recorded the mass of the baby food jar with the copper and then subtracted the previous mass of the baby food jar with no solution to find out the mass of product we had. Then it was time to start calculations. A single replacement reaction took place place but the charge of iron was unknown so we had to create a balanced chemical equation for each possible charge of iron (2+ or 3+) and find theoretical yield of each then use our percent yield formula to calculate which had the highest percent yield; therefore, telling us the charge of the iron. After calculations were done, it was found that iron with a 2+ charge created a percent yield above 100% which is impossible, so the charge on iron in or reaction was 3+.

Here are some pictures of the lab:

Percent Yield

The basic formula for percent yield is:

Use your knowledge of stoichiometry and limiting reagent (with the help of my two previous blog posts) to solve for theoretical yield. Actual yield comes from the results of your lab.
The following practice problems  can help solve for percent yield:  http://tmlimitingreagents.weebly.com/percentage-yield-and-actual-yield-practice-problems.html

Limiting Reagents

We learned two approaches to solve limiting reagent problems:

Approach 1:
1. Balanced chemical equation
2. Convert all info to moles
3. Calculate the mole ratio from the given info. Compare calculated ration to actual ratio.
4. Use the amount of limiting reagent to calculate the amount of product produced.
5. If necessary, calculate how much is left in excess of non-limiting reagent

Approach 2:
1. Balanced chemical equation
2. Convert info to moles
3. Use stoichiometry for each individual reactant to find mass of product produced
4. The reactant that produces lesser amount is the limiting reagent
5. The reactant that produces larger amount is excess reagent
6. To find amount of remaining excess reactant, subtract the mass of excess reagent consumed from total mass of excess reagent given.
**This approach is the one I prefer to use

The following video and link can be used for extra practice:
https://www.khanacademy.org/science/chemistry/chemical-reactions-stoichiome/limiting-reagent-stoichiometry/v/stoichiometry-limiting-reagent
http://www.chemteam.info/Stoichiometry/Limiting-Reagent.html

Stoichiometry

Solving problems using stoichiometry uses a balanced chemical equation. Then you start with what is given. Convert grams of the given substance and convert to moles using the periodic table, then multiply by the mole ration from the balanced chemical reaction, and finally back to grams using the periodic table again. Here's a chart to map it out a bit better:

The following video can help explain more: https://www.youtube.com/watch?v=SjQG3rKSZUQ

Here are some practice problems:  http://www.chemistry.wustl.edu/~coursedev/Online%20tutorials/Plink/Stoichiometry/stoichset.htm