Wednesday, February 9, 2011, David Colston

1)First, we picked up two new worksheets. The page numbers were 33 and 34, and they had the same title: Limiting Reactants 4

2) We then proceeded to go over the Penny lab we did in class. In the Penny Lab, we put the CuCl2 and the nails in water and stirred it up. After stirring it for a while, the blue-tint to the water caused by the Copper Chloride disintegrated, and the water remained there. By this we know that CuCl2 is the limiting reactant, but you can also do this by writing the problem out like this:

First you must balance the equation, so it would be:

3CuCl2 + 2Al ----> 2AlCl3 + 3Cu

Then, you need to put your data in your tables:

3.0 grams CuCl2	1 Mole CuCl2	3 Mole Cu	63.55 grams Cu
	134.45 grams CuCl2	3 Mole CuCl2	1 Mole Cu

Answer: 1.417 grams Cu - We know this is the limiting reactant because CuCl2 has less then the Excess reactant, Al

1.25 grams Al	1 Mole Al	3 Mole Cu	63.55 grams Cu
	26.98 grams Al	2 Mole Al	1 Mole Cu

Answer: 4.416 grams Cu - Excess Reactant... Can only make as much as the limiting reactant though, so it can only make about 1.4 grams of CuCl2

To answer the second question, we can go backwards from grams needed to grams CuCl2.

3) We went over quiz number 4

A.

12.5 grams Al	1 Mole Al	2 Mole Al2O3	101.96 grams Al2O3
	26.98 grams Al	4 Mole Al	1 Mole Al2O3

12.5 grams O2	1 Mole O2	2 Mole Al2O3	101.96 grams Al2O3
	32.00 grams O2	3 Mole O2	1 Mole Al2O3

Answers

A. 23.6 grams Al2O3 = Limiting Reactant

and

26.6 grams Al2O3 = Excess Reactant

B. The mass of the product can only be as much as its limiting reactant, so it would equal 23.6 grams

4) We went over a problem on page 33

Problem Number 2: 2NH3 +5F2 ----> N2F4 +6HF

If 120 g of NH3 is allowed to react with 590 g of F2,

What mass of HF can be formed?

120 grams NH3	1 Mole NH3	6 Mole HF	2 grams HF
	17.04 grams NH3	2 Mole NH3	1 Mole HF

Answer =422.7 grams HF or 420 grams HF (Sig Figs)

590 grams F2	1 Mole F2	6 Mole HF	20.01 grams HF
	38 grams F2	5 Mole F2	1 Mole HF

Answer= 372.8 grams HF or 370 grams HF (Sig Figs)

Limiting Reactant

What is the Excess Reactant?

372.8 grams HF	1 Mole HF	2 Mole NH3	17.04 grams NH3
	20.01 grams HF	6 Mole HF	1 Mole NH3

120 grams NH3 -105.8 grams NH3=14.2 grams NH3 or 14 grams NH3 (Sig figs)

5) We took Quiz Number 5, covering the things that we learned in class today (That are on here)

6) We went over the newest Lab, that is just one day out of our 3 day lab test. If you missed yesterday, you may want to see Mr. Tucker, but it isn't the end of the world seeing as we only spent about 10 minutes on it. What we began to do was: We put the CuCl2 and the nails in water and stirred it up. The nails become a rusty gray color. We will work more on this in class tomorrow.

HOMEWORK/NOTES: PREPARE FOR QUIZ, AND FUTURE QUIZZES. IF YOU DON'T UNDERSTAND SOMETHING, GO OVER IT OR GET HELP WITH MR. TUCKER, A FELLOW CLASSMATE OR IN THE TLC. DO AS MUCH OF PAGE 33 and 34 AS POSSIBLE. THINK ABOUT THE LAB EXAM!!!

If you read this, thank you! I hope it was a help!