CHEM 225 – Quiz #1
1. (3 pts) List three important concepts that you learned from doing Lab #1
2. (3 pts) If you have to make 500 mL of a solution of NaCl that is 0.5M KCl, how much
KCl in grams do you need to weigh out?
3. (8 pts) DEFINE the following:
a. TD (on a buret)
b. TC (on a volumetric flask)
c. Accuracy
d. Precision
4. (6 pts) State whether the following errors are systematic (determinate) or random.
a. A 25-mL transfer pipet consistently delivers 25.031 +/- 0.009mL.
b.
analytical balance calibration error
c.
reading the buret as 32.10mL and then as 32.11 mL
BONUS: (+2 pts) In Lab #1, you used micropipettes. If you needed to measure out 100µL of
dye solution, you set the micropipette to deliver 100µL and then did your work. In a sense, you
took for granted that the pipette was going to deliver exactly 100µL. How could you have
checked the accuracy of your pipette so that you could be sure that it was delivering 100µL?