Unit Exam

Today, we took the unit test for stoichiometry. I think that I did better than I anticipated, but it was definitely easy to make mistakes. Especially since there was two times that 2 or 3 questions went with one reaction/equation, so if the first question was messed up, then so were the rest. I felt like I had an easier time on the test than the quiz, but I'm just really anxious to get my score back.

One thing I hate to admit, but I struggled on remembering polyatomics... Specifically chlorate. I ended up getting it, but it definitely took me some time to remember. Also, I think the hardest thing for me with this unit was simply the way that the questions were worded. I know how to do stoichiometry pretty well, but when different types of information is given in a question with different formats, I get confused.

All in all, I enjoyed this unit. Unlike the rest, it was a basic background that simply needed to be applied in different ways, whereas other units had a lot of different concepts to apply.

Here is a video that reviews stoich:
http://www.chemteam.info/Equations/SingleReplacement.html

And this is a source that also reviews, but provides a broad array of information with review problems as well: http://www.chemteam.info/Stoichiometry/Stoichiometry.html

Day 2 and 3 of Copper (II) Chloride Lab

We have completed the lab. On day 2, we simply took the nail out of the copper (II) chloride solution and used hydrochloric acid and distilled water to wash the copper, and then left it to dry over the weekend. On day 3, we weighed the nail and the jar with the solid copper. For mine and Bri's lab, we found out that we produced a 3+ ion of iron.

Below are pictures of day 2:


And day 3:



Below is a link that explains single replacement reactions:
http://www.chemteam.info/Equations/SingleReplacement.html

Percent Yield

Percent yield is probably the easiest part of stoichiometry. After calculating the theoretical yield (what should be produced) and knowing the actual yield (what was actually produced), you simply plug these two numbers into a formula to find out the percent of the theoretical yield that was yielded from the experiment. This comes after all the hard stuff, which is the actual stoich that is being calculated.



This are two videos that go through this concept:
http://study.com/academy/lesson/how-to-calculate-percent-yield-definition-formula-example.html
https://www.youtube.com/watch?v=LicEaaXhlEY

Copper (II) Chloride Lab

Today in class, we did the first day of the Copper (II) Chloride Lab. This simply consisted of preparing the nail in the solution to be decomposed. We measured the jar and copper (II) chloride, and we then combined this with water in the jar. After mixing it so the crystals dissolved, the appearance was a bold blue liquid. We placed the nail in the solution, and now we simply wait for the copper (II) chloride to react with it.

Here are some pictures of the lab:


Also, below is a source that synthesizes chemical reactions and stoichiometry:
https://www.khanacademy.org/science/chemistry/chemical-reactions-stoichiome

Oxidation Rules

1. pure elements (stand alone elements) have an oxidation number of zero
2. for monoatomic ions (metal elements), the oxidation number is equal to its charge
3. fluorine alway has an oxidation number of -1 when in compounds
4. Cl, Br, and I always have an oxidation number of -1 in compounds, except when combined with oxygen or fluorine
5. the oxidation number of H is +1 and of O is -2 in most compounds.
• exceptions for H: in compounds with metals, H is -1
• exceptions for O: in peroxides, the charge is -1
6. the algebraic sum of the oxidation number for the atoms in a neutral compound must be zero; in a polyatomic ion, the sum must be equal to the charge of the ion

Here are a couple references that help explain:

http://www.dummies.com/how-to/content/rules-for-assigning-oxidation-numbers-to-elements.html

http://www.wikihow.com/Find-Oxidation-Numbers

element	usual oxidation state	exceptions
Group 1 metals	always +1
Group 2 metals	always +2
Oxygen	usually -2	except in peroxides and F2O (see below)
Hydrogen	usually +1	except in metal hydrides where it is -1 (see below)
Fluorine	always -1
Chlorine	usually -1	except in compounds with O or F (see below)

Metals Lab

Today, we did a lab testing the reactivity of some metals with different solutions, such as water and HCl. It was interesting to see reactions of metals first-hand and how different things reacted. For example, some bubbled and fizzed, some smoked, and some simply changed colors. All in all, we had to mak our own reactivity series depending on the results, and this helped me better understand this concept by making my own and just witnessing it myself. Below is a picture of some of the reactions!

Here is an example of a reactivity series. As shown, the elements towards the top are the mots reactive with most things, and vice versa.

Also, here is a link that explains reactivity series: http://www.bbc.co.uk/education/guides/zqjsgk7/revision