Week of 10/26

Monday: Gas Laws Simulation Lab

Tuesday: Today we went over the Dumas method of determining molar mass.  We did #13 in the packet (and connected to empirical formula).  Then I gave you a copy of this set of procedures and data to see how you could do this experimentally.  Real value was ethanol.  The last bit of class we worked on multiple choice problems and I pointed out how with gases at the same T and P, volume ratios could be considered the same as mole ratios.

Wednesday: Today we started out finishing the multiple choice questions in your packet as well as predicting reactions, recalling net ionic and drawing pics.  The biggest takeaway is that metals are always solid and do not have charges and do not dissolve when mixed with water (they react, but are not soluble in their elemental, non-ionized, form).  Also when drawing gases, make sure to draw them outside the beaker.  Next we went over Dalton’s law of partial pressure and did the more advanced calculations involving mole fraction, collecting a gas over water and what pressure and volume to use in PV=nRT when you have a mixture of gases.  For the last 20 minutes you planned the next design lab.  The goal is to design a lab to measure R for two different gases and to see that the R’s are the same for different gases and to compare to accepted value.  Today’s notes (including answers for MC) are here.

Thursday, Friday:   Design lab

Monday: Finish lab/ Review

Wednesday: Test

Week of 10/19

Monday: Your goal is to figure out which alkali metal it is.  As a group you will write procedures that will both explain the procedures and the calculations behind the procedures.  You will do the lab on Monday and hopefully have enough time to do the calculations. Homework will be to write a conclusion.  Grades will be: Data Collection, Experimental methods (grade based on procedures and evaluation of procedures), and Math.  Notes and lab instructions.

Experimental Methods Math Data Collection and Presentation
 Shows thorough understanding of method, thorough explanation of a detailed plan (procedures, including calculations) as we as thorough evaluation of results.  Demonstrates thorough ability to apply mathematical process and can justify their use. (clearly labeled calculations w/ any assumptions stated, inc. Just and application of s.f. Rules)  Thorough measurement technique, presents data clearly and correctly.
 Less thorough, but competent Demonstrates ability to apply mathematical routines and can sometimes justify their use. Less thorough. (s.f., labeling)
 Lacks justification  Demonstrates ability to apply mathematical processes to solving chemistry problems. Poor technique. (miss. Est. dig, +/-)
Discussion or plan is weak or missing too much. Demonstrates some ability to apply mathematical processes to solving chemistry problems Missing essential information
 No Evidence  No Evidence  No Evidence

So for Methods/Error Analysis make sure you:

  • Calculations
    • Show work/ justify with words as you go along like you did on mixtures lab
    • Justify number of sig figs in final molar mass.
    • Calculate percent error.
      • Sample 1 was Na
      • Sample 2 and 3 were K
  •  Procedures
    •    Say what you are doing (steps),
    •    why you are doing it that way (rationale for choices),
    •    how you will get an answer (calculation), including plan for certain sig figs
  • Error Analysis/Conclusion
    • Limitations of method/equipment/conclusions,
    • discussion of variability (precision…number of decimal places since you don’t have multiple trials) and accuracy (percent error) of the data that is justified
      • State the error
      • Determine whether it was random or systematic and justify this
      • What effect did the error have on the results – in detail. Do math if necessary. Do not just say it would throw off the result. Give an example.

Lab due MONDAY October 26th.

Tuesday: Review for test

Wednesday: Test.  Homework is to work on conclusion (nevermind about videos)

Thursday: Gas laws notes and practice.

Homework:  Make sure you do #5.119 before class tomorrow!

  • Gas laws; 5.39-5.49 (odd only)
  • 57, 59, 73, 117,119 (ideal)
  • 5.63, 67, 69, 71 (molar mass and density)

Friday: Today we are going to start with learning other reactions that produce a gas then do the baggy challenge. Next we will get into kinetic molecular theory including real vs. ideal gases. Here’s the notes.

Homework: finish conclusion and other textbook problems (5.27,28, 33, 142, 21, 22, 23)

Week of 10/12

Monday: No school – Columbus Day

Tuesday: Today we went over gravimetric analysis (see videos on unit 2 page if you missed them or need help).  I showed you how vacuum filtration works and we did the lab based problem on page 22 of the packet.  This is actually the answer, but we just covered up the answer and went through the problem on a separate sheet of paper. The rest of class you worked on other gravimetric analysis problems 4.83, 4.85, 4.87.

Wednesday: No class cuz you were all taking the PSATs

Thursday: Today we started by going over the terms saturated, unsaturated, soluble, insoluble and partially soluble – and drew pictures for them. The key to showing the difference between saturated and unsaturated is to know the solubility limit of the compound.  If there’s a lower molarity than the solubility limit = unsaturated, if = molarity to solubility limit = saturated.  Saturated solutions are easy to detect if enough has been mixed that a precipitate has formed.   Then we worked on practice problems in the packet – pages 15 and 16.  3 answers on page 16 are wrong on the key (key is on page 23).  The net ionic reaction for #9, 10 and 11 should have the solids in them since solids are included in net ionic reactions.  When I wrote the answer key I wrote the net ionic rxns as if they solids were aqueous. So here’s the answer for number 12) Fe(HCO3)3 + 3H+(aq) –> 3H2O(l) + 3CO2(g) + Fe3+(aq)

Homework: Neutralization problems: 4.31, 89, 91, 93 and rest of gravimetric analysis problems: 4.115, 4.117, 4.119

Friday: Today we are going to start with page 19 in your packet…multiple reactions and mole ratios! It turns out that you can string mole ratios from one reaction to another reaction, you can multiply reactions times a coefficient and you can add reactions together.Then your goal is to write procedures for a lab…here’s the premise: I am going to give you a sample of an alkali metal carbonate – basically a white powder that you know has a carbonate ion and an alkali metal ion, but you don’t know which alkali metal it is.  Your goal is to figure out which alkali metal it is.  As a group you will write procedures that will both explain the procedures and the calculations behind the procedures.  You will do the lab on Monday and hopefully have enough time to do the calculations. Homework will be to write a conclusion.  Grades will be: Data Collection, Experimental methods (grade based on procedures and evaluation of procedures), and Math.  Notes and lab instructions.

Week of 10/5

Monday: Review for the stoichiometry test tomorrow.  We started with homework problems and it became apparent that most of you had not done much limiting reactant work so we started going over the first problem on the limiting reactant section.  This was helpful because some of you were thinking of this in terms of atoms rather than molecules…you must use mole ratio, can’t just total up all the atoms of each type and then figure out the limiting reactant since reactions won’t always occur like that.  I also showed 3 different ways for figuring out excess and then asked you guys to write down your preferred method.  The rest of class we worked more LR problems.  In the last few minutes we did a combustion analysis problem just to refresh your memory.

Tuesday: Test on stoichiometry.

Homework: Dilution and molarity videos. The first two listed are the ones I think you need to watch even though you’ve seen 2.b.1.5.   The next 3 are only if you truly don’t remember molarity at all or have difficulty calculating the number of ions from the moles of an ionic compound (like how many moles of nitrate ions in 54.0 g of Cu(NO3)2?)

Watch these three only if you need them!

  • 2.b.1.1 Intro to Solutions (From first year chem – if you want to review vocab like solute and solvent.  Molarity is introduced near the end.)
  • 2.b.1.2 Molarity (from first year chem, just shows the math for various problems, but doesn’t explain what molarity is)
  • 2.b.1.3 Moles of ions (This is not about molarity, but is about using subscripts to determine moles of ions something you will need to do molarity of ions)

Wednesday: 

Today we reviewed the process of dissolving for both ionic and covalent compounds and I gave the definition of electrolyte.  We worked on 4.20 in the textbook which unlike last year was not confusing at all…no one had any questions really.  So the rest of class we worked on various molarity and dilution problems including  showing how to solve various problems.  Notes from last year (which have a bit more detail as I had to review a number of concepts that we didn’t have to review this year) are here.  Notes from this year are here.

  • basic molarity (but see chem 1 videos for more if you need it)
  • molarity w/ multiple solutions
  • dilutions
  • molarity mixing two solutions
  • dealing w/ mass percent.

Homework: textbook problems and packet (page 1 on molarity of ions, page 2 on molarity w/ multiple solutions and dilutions)

Thursday: We started by learning to prepare solutions using volumetric flasks and then you prepared calcium chloride and sodium oxalate solutions in preparation for lab tomorrow.  The rest of class you spent reviewing naming acids rules and practicing.

Friday: Today we started by predicting double displacement reactions including two special types: neutralization and acids with carbonates. We went over complete ionic, net ionic, spectator ions and  and drawing pictures. Here’s the notes. Second half of class you completed the chemical formulas lab (will need to be logged in to APS google to open).

Homework: write-up