Friday, August 28th

We competed the Copper / Iodine lab today. Remember, you are trying to confirm with all of your trials is either CuI or CuI2. You should hope to confirm the same ratio in all of your trials. For your write-up, which is due Monday, August 31, you need to follow the following format.

First, have a discussion of the theory behind the lab. This would include what the lab is trying to accomplish and how this will be accomplished. Discuss the science behind the lab procedure. This section (please label all sections) should consist of a 3 to 4 sentence paragraph. Do a good job, but get to the point. Do not discuss what you actually did while doing the lab.

Second part, the data table. This should be neatly organized showing the data from each trial. Remember to include all units of measurement. There will be no calculations done in the data table.

Third part, analysis. This is where all calculations are to be done. Make sure to perform the calculations for each individual trial. Do not average any data for this lab because every trial was different.

Fourth part, SEE's (Sources of Experimental Error) This will probably be the most scrutinized part of the lab report. This is where you really critique your results. Please discuss sources of error that would effect your outcomes. Talk about random or systematic errors that will cause you to be away from the expected one to one ratio or one to two ratio. Also, you may have different ratios from trial to trial. They may be correct (one trial 1:1, another 1:2), but the inconsistency is an error. Please never say the following in the SEE's section: (1) Human Error - you should be able to be specific about an error in the lab, do not give the lazy answer of human error. (2) "My calculations were done wrong." The do them right. Calculations are not part of the lab procedure.

Fifth part, conclusion. Please state if the purpose or intent of the lab was achieved. Give the evidence as to why or why not the purpose or intent was achieved. Also, include a statement on how you would inprove the lab, whether it be procedure or equipment, etc, to optain better results if you had the chance to do the lab over again.

Remember, you should keep all of your labs in a portfolio to present to a college or university if you pass the AP Chemistry exam in the spring. Therefore, you are not only doing this lab report for a grade in this class, but also to be critiqued by the faculty at a college or university to give you credit. So you want to do a good job and make it look professional.

Look to have our first major exam next Thursday, September 3rd. Have a good weekend.

Thursday, August 27

Tomorrow is Game Day (i.e. we are doing a lab). Today we went over the pre-lab for the synthesis of copper and iodine lab. I would like it if you tried the mock calculations for tomorrow. I messed up during 2nd hour by doing one of the calculations wrong, so I am going to make the correction here to get people on the right path. All calculations pertain to the scenario's given in the pre-lab.

First scenario:

First, 7.634 g. minus 7.608 g. is the correct way to find the grams of copper consumed in the reaction. (0.026 g. of Cu which will become 0.00041 mol Cu).

Second, (my screw up) 7.732 g. minus 7.608 g. (the mass of the copper at the end of the lab) is the correct way to find the mass of the copper iodide compound. (0.124 g. of Cu(x)I(y) compound)

Third, the mass of the iodine consumed in the lab is 0.124 g. minus 0.026 g. This gives a mass of 0.098 g. of iodine which will become 0.00077 mol I.

Another way to find the mass of iodine would be to take the mass of the compound (7.732 g.) minus the original mass (7.634 g.). This too give 0.098 g. of iodine. This is the most direct way and I should have thought of it in class. Any mass added to the original copper must come from the addition of iodine. OOPS!

The first scenario's empirical formula is Cu(0.00041/0.00041=1) I(0.00077/0.00041=1.88)
-->CuI(2)

Second Scenario (calculated the same way)

Cu --> 7.608 g. - 7.583 g. = 0.025 g. Cu --> 0.00039 mol Cu
I --> 7.661 g. - 7.608 g. = 0.053 g. I --> 0.00042 mol I

Cu (0.00039/0.00039=1) I (0.00042/0.00039=1.08) -->CuI

Remember, copper will only have two possible oxidation numbers, (+1) or (+2), so tomorrow's lab is intended to prove one of them. Therefore, your data may need to be massaged to meet the possible ratio's that correspond to the probable oxidation states of copper. Examples: 1.67 would not be multiplied by 3, but rather in this scenario, rounded up to "2". The value 1.25 would not be multiplied by 4, but rather rounded down to "1".

Wednesday, August 26th

Homework: pages 126-128, problems 87, 88, 92, 94(a,d,f), 95(b)
Hint for problem 95 b, you will need a mass value to convert to moles to find the limiting reactant. You are given volumes and densities of the two liquid reactants. Remember, density is mass divided by volume, so solve the three variable equation for mass, then convert to moles.

Tuesday, August 25th

Homework: page 125 problems 67, 69, 70, 71, 72, 73
Problem #70 gives you the molar mass indirectly by giving a mass amount and the number of moles associated with the mass amount. Remember, molar mass is reported as grams per mole. Reading comprehension for #73 is key to understanding the problem. The word "only" in the first sentence is key. You also have to reason with the vagueness of the real molar mass.

Monday, August 24th

Homework for this evening (pages 123-125) Problems 21, 22, 23, 24, 54(a-b), 62(a-b), 63, 64, 65, 66 Those problems in bold have already been completed in class or started.

Friday, 8/21 - My Birthday

No homework for this weekend. Y'all need to do a little LIVIN. Maybe look over Sections 3.1-3.5 in the book if you are having trouble falling asleep. Take care and be ready to work come Monday.

Thursday, 8/20

Sorry to be so late on this post of today's activities. We went over diagnostic test in class. This will be curved and placed in the homework category of your grade. Homework for 8/20 was to read Chapter 3, Sections 3.1 through 3.5. On page 77 of your text, you are to complete problems 67 and 69. These two problem sets cover writing compound formulas and names.

It has been a while since I last posted. Thanks to all of you that have emailed me for the year's first extra credit assignment. I just wanted to remind everyone that there is an OPTIONAL review session at Heritage on Thursday, August 13th from 6:00 to 9:00 pm if you are interested. This is not mandatory. It is only for those that feel that they need some refreshing of material that was taught in either honors physical science or chemistry. You do not have to stay the whole time and you can come whenever you wish. Hope to see you there.

Mr. Brueckner