DATE ________________
NOTES-59A-MASS% AND MOLARITY (STUDENT)
CHEM 110 (BEAMER)
NOTES-59A: Molarity-01
XXX
XXXxxx
Mass Percent and Molarity
General Information

You will need your calculators and the periodic table

Textbook: 13.9
I.
Review of Solutions:
II.

Amount of particles of solute per chosen volume of solvent or solution

Review: %(w/w) also known as “mass percent” or “percent by mass”



Sample Problem 1:
A 40.00-gram sample of sucrose is dissolved in 520.0 mL of water. Determine the concentration (mass%) of this
solution. (As always, if an equation is used, you must write the “variables-only” initial equation. Note: you need
one piece of information that should be memorized at this point. I will not remind you of this on tests.

Sample Problem 2A:
An aqueous sodium bicarbonate solution has a total mass of 800.0 grams. If the solution is 14.3%(w/w) sodium
bicarbonate, calculate the mass (in grams) of sodium bicarbonate? Hint: Use the mass percent as a conversion
factor.

Sample Problem 2B:
Based upon your answer to Sample Problem 2B, what is the mass of water in the solution?
Page 1 of 3
DATE ________________
NOTES-59A-MASS% AND MOLARITY (STUDENT)
CHEM 110 (BEAMER)
III.



This can be used as a

You must learn that whenever you see
You should also see

Sample Problem 3
Calculate the molarity of a solution prepared by dissolving 0.234 grams of NaCl in 50.00 mL of water.



This is called a
0.801
sodium chloride solution
Sample Problem 4: Calculate the moles of KCl present in 55.2 mL of a 2.25 M KCl solution.

Hint: use molarity as a


Therefore:
Convert your answer to grams.
Page 2 of 3
DATE ________________

NOTES-59A-MASS% AND MOLARITY (STUDENT)
CHEM 110 (BEAMER)
Sample Problem 5: Calculate the volume (in mL) of a 0.180 M HCl solution that contains 0.125 moles of HCl

Again: use molarity as a
VII.
Summary

If you are given mass of solute (or moles of solute) and volume, use the molarity equation to determine molarity.

Use molarity as a conversion factor if

You are given molarity and volume, and you are trying to find moles (or mass)

You are given molarity and moles (or mass), and you are trying to find volume.
Page 3 of 3