Chemistry Recording for 3/31 - Figuring out oxidation numbers

http://youtu.be/Fzsxfkr5dqk

3/31 Chemistry update and homework due 4/7

Hi folks,

Today we stepped into another aspect of chemistry with oxidation and reduction reactions.  We went over the rules of finding oxidation numbers today and we will get into half reactions and electron transfers next week.  

From here on out, the material should be quite a bit easier.  We've finished stoichiometry with is some of the hardest material of the year.  After oxidation and reduction, we will be covering acids and bases and then we will get to the gas laws.

For homework this week I'd like you to find the oxidation numbers for each of the elements in the following molecules.

1.  LiNH2

2.  N2H2

3. Ca(NO2)2

4. CO2

5. BF4-  (Notice the - on this one)

6. PO4 ^3-

7.  ClNO

8.  S8

9.  MnO2

10. H2SO4

11. CO3 2-

12.  MgCl2

13.  KNO3

14. SF6

Answers:

1. Li +1 N -3 H +1

2. N-1 H +1

3. Ca +2 N +3 O -2

4. C +4 O -2

5. B +3  F -1

6. P +5 O -2

7. Cl -1 N +3 O -2

8. 0

9. Mn +4 O -2

10.  H +1 S +6 O -2

11. C +4 O -2

12. Mg +2 Cl -1

13.  K +1 N +5 O -2

14. S +6 F -1

Chemistry Recording for 3/24 class - Limiting reagents and naming review

https://youtu.be/561ePSneqLw

Formulas for labwork

Hi folks,

In case you don't have them here are the formulas for the lab work this week.

C2H4O + NaHCO3 —> H2O + CO2 + NaC2H3O2
Acetic acid Baking Soda Sodium Acetate
in vinegar

3/24 chemistry class update and homework due 3/31

Hi folks,

Today we primarily did a lab dealing with limiting reagents but we also spent a bit of time reviewing the math of limiting reagents and naming ionic compounds.

The latest quiz seemed to indicate that many folks haven't quite mastered the concept of naming ionic compounds so for homework this week I'd like you to do a bit more work on that by doing some naming as well as answering questions about today's lab.  Answers are included for the naming section.

1.  What was the limiting reagent in the first trial?  

2.  How much excess reagent did you have in the first trial?

3.  What was the limiting reagent in the second trial?

4.  How much excess reagent did you have?

5.  What was the limiting reagent in the third trial?

6.  How much excess reagent did you have?

7. In a perfect world, how much baking soda and vinegar would you need to yield 300 g of sodium acetate?

8. Name the following compounds.

a.  AgCl3

b. CrO

c. CaI2

d. Zn2Br2

e. Fe2O3

f. FeO2

g. SrI2

h. Zr(OH)2

i. V(NO2)2

j. Ag(SO4)

k. Mn(PO3)

Answers to Names

a.  Silver (III) Cloride

b. Chromium (II) Oxide

c. Calcium (II) iodide

d. Zinc (I) Bromide

e. Iron (III) Oxide

f. Iron (IV) Oxide

g. Strontium (II) Iodide

h. Zirconium (II) Hydroxide

i. Vanadium (II) Nitrite

j. Silver(II) Sulfate

k. Manganese (III) Phosphite

Recording of 3/17 Chemistry Class - Limiting Reagent and Percentage Composition

https://youtu.be/TTWyWVb1JFA

3/17 Chemistry update and homework due 3/24

Hi folks,

Lots of math today. We took a look at how to figure out percent compositions and how to find the limiting reagents in a chemical reaction.

Homework due next week is to do the enclosed .pdf and answer the following questions.

1. What is the percent composition of oxygen in ZnSO4?

2. What is the percent composition of Mn in KMnO4?

3. Calculate the empirical formula of a compound with a percent composition of 88.9% oxygen and 11.1% hydrogen.

4. Calculate the empirical formula of a compound with a percent composition of 49.5% carbon 5.2 % hydrogen 16.5% oxygen and 28.8% nitrogen.

Formulas for chemistry lab work

Hi folks,

Some folks don't have the sheet for the lab work they need to do so here are the formulas.  Formula's:  Glue C4H6O2, Borax Na₂B₄O₇·(10H₂O)

Remember, no class on 3/10 due to spring break.

See you all next week.

Never Stop Wondering

"Science Jim"  Mueller

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3/3 Chemistry update and homework due 3/17

Hi folks,

First off, NO CLASS NEXT WEEK. We have spring break next week so we won't be holding class.

Second, no video of class this week. Just about the entire class was spent doing the lab, so there was nothing much to record.

Today we took the time to do another lab. I had the students create silly putty using water, borax and glue. The point of the experiment was to carefully measure the masses of the three different substances and determine the ideal ratios of the materials needed to create just the right amount of silly putty with nothing left over.

Homework for this week is to:

1. Figure out (if you haven't already in class) how much water, borax and glue you would need to create 1000g of silly putty with nothing left over.

2. Using the masses you found in class, calculate how many moles of materials you used to create your "perfect" silly putty. The formulas for Borax and glue are on the sheets you received in class. Borax has a very strange formula with a 10H2O thing tacked to it. That's what happens when it combines with water.

Read pp. 271 - 279 in the Conceptual Chemistry book.
Do exercises pg. 303 #'s 1 - 9
Do problems pg. 304 #'s 1-4