Exam 2 Notes

(4/24/20, bes)

Day 1 - Question

1a) (3 pts) Basics of UV-Vis determination of unknown concentration -- Check!

1b) (3 pts) What is the molar absorptivity coefficient (ε) --> this is given = slope with units of 1/(nM cm) <-- units are important!!!

1c) (3 pts) x1, x2, x4, x8 is a serial dilution. All UV-Vis standards should be made via serial dilution, NOT individually. Yes it is true that standards must cover the full range of sample absorbancies, but this does not address the question asked.

2a) (6 pts, 2 each) Dye D --> blue shifted (smaller box), Dye E --> main, Dye F --> red shifter (larger box)

2b) nowhere to be found (errata)

2c) ~69 nm, ~152 nm, ~244 nm; must use the # of π-electrons to determine the n_f and n_i states --> (n_f² - n_i²), math errors can occur if not careful.

Range of scores out of 30 pts: 18 pt --> 30 pts, ave score: 25.2 pts.

Day 2 - question

Range of scores out of 30 pts: 18 pt --> 30 pts, ave score: 24.6 pts.