1. Welcome (Dec 13) Today in class: Today Lab Friday in class
Quiz on all we have done so far in Unit 4 (short – 20 min)
Lab 15 – construct calibration curve!
Today Lab
Finish Lab 15, work time on post-lab (Due F in class)
A little more practice in LeChatelier
Friday in class
Discuss Lab 15 results, Integrated practice problems on units 1-4, quiz corrections, MC review A (MC review B in study sesh)

2. Lab 15 Time! The plan (class and lab):
Part 1: Calibration Curve reference solutions – group 1
Part 2: Test solutions – group 2
Part 3: Calculate concentrations, make calibration curves, and finish calculations and qs (in lab and at home)

3. Lab 15 – Finding the K of FeSCN2+
Fe3+ (aq) + SCN- (aq)  FeSCN2+ (aq)

4. Lab 15 What do you need to do – reference solutions?
Calculate the concentrations of everything in all 10 solutions (In Sheets but show ONE example calculation in lab book)
This processed data table should go in your lab book
Show one example calculation set done by hand
Make a calibration curve in Sheets or LP with your 5 reference solutions (also with 0,0 as a point), and fit a trendline to find the equation.
Obviously, calibration curve graph printed/taped in WITH equation for the linear fit
Don’t forget R2 value tells you how awesome the line is!
Show your math work! Units! Reasonable sig figs!
The biggest assumption you need to make is with your concentrations of FeSCN2+ in the reference solutions so that you can make your calibration curve.  It's just a limiting reagent problem.  You used WAY more Fe3+ than you needed, so it is your excess reagent.  The concentration of FeSCN2+ at equilibrium we will assume is EQUAL TO the starting concentration of SCN- (your limiting reagent) because the overwhelming excess of Fe3+ would shift the equilibrium to completion (all FeSCN2+).  That is how you know your concentrations for your calibration curve.

5. Lab 15 What do you need to do – test solutions?
Find the concentrations of FeSCN2- in each of the 5 TEST solutions by using your trendline equation (by interpolation).
This is “x”
Show one example in lab book, the rest can be entered in your Excel sheet
Do ICE tables to find the K constant for the reaction for all the test solutions using “x” you found on your graph.
Show one example by hand in lab book, rest in Excel/Sheets
Find the average K from all reliable trials.
Post-lab questions: 10 and 11 only (the rest are just calculations)
ALL IN YOUR LAB BOOK. Due Friday
Show your math work! Units! Reasonable sig figs!
The biggest assumption you need to make is with your concentrations of FeSCN2+ in the reference solutions so that you can make your calibration curve.  It's just a limiting reagent problem.  You used WAY more Fe3+ than you needed, so it is your excess reagent.  The concentration of FeSCN2+ at equilibrium we will assume is EQUAL TO the starting concentration of SCN- (your limiting reagent) because the overwhelming excess of Fe3+ would shift the equilibrium to completion (all FeSCN2+).  That is how you know your concentrations for your calibration curve.

6. Homework Day 4
For Friday: Lab 15 all done in lab book (see handout for expectations)
Remember the optional study Webassign for review!
STUDY YOUR BUNS OFF FOR THE EXAM!!!!