BUCOL, Joana Margarette O.
BS BIOLOGY II
August 4, 2020
ANALYTICAL CHEMISTRY
Exercises:
1. A 12.5 mL portion of a solution is diluted to 500.0 mL, and its molarity is
determined to be 0.125 M. What is the molarity of the original solution?
Given:
V1 = 12.5 mL
V2 = 500.0 mL
M2 = 0.125 M
Asked:
M1 =?
SOLUTION:
M1V1 = M2V2
𝐌𝟏 =
M1 =
𝐌𝟐 𝐕𝟐
𝐕𝟏
𝐌𝟐 𝐕𝟐
𝐕𝟏
=
𝟎.𝟏𝟐𝟓 𝐌 × 𝟓𝟎𝟎.𝟎 𝐦𝐋
𝟏𝟐.𝟓 𝐦𝐋
= 𝟓 𝐌 = 𝟓. 𝟎𝟎 𝐌
Calculator Answer: 5 M
Final Answer: 5.00 M (there are 3 significant figures)
2. You wish to prepare 500 mL of a 0.100 M K2Cr2O7 solution from a 0.250 M
solution. How many mL of the 0.250 M must be diluted to 500 mL?
Given:
M1 = 0.250 M
M2 = 0.100 M
V2 = 500 mL
Asked:
V1 =?
SOLUTION:
M1V1 = M2V2
𝐕𝟏 =
𝐌𝟐 𝐕𝟐
𝐌𝟏
𝟎. 𝟏𝟎𝟎 𝐌 × 𝟓𝟎𝟎 𝐦𝐋
𝐕𝟏 =
= 𝟐𝟎𝟎 𝐦𝐋
𝟎. 𝟐𝟓𝟎 𝐌
Calculator Answer: 200 mL
Final Answer: 200 mL (there are 3 significant figures)