M
 Solute must be in MOLES: conversion between moles and grams. grams of solute
----->
<----- divide grams by molar mass of the solute multiply moles by molar mass of the solute
----->
<-----
 Volume must be in LITERS: conversion between liters and milliliters.
-----> multiply by
1000
-----> liters of -----> solution
<----- divide by 1000 <-----
moles of solute mL
<----- of solution
1. Determine what the problem is asking you for.
2. Write down all the information given to you in the problem.
3. Make conversions necessary: moles and liters.
4. Use the triangle above to determine the unknown.
5. Make final conversions if necessary to give the required result.

Example 1:
How many grams of AgNO
3
are required to prepare
500 mL of a 2.50 M solution?
Info asked for:
 Grams solute needed (AgNO
3 find moles AgNO
3
): We will first
, then convert to grams.
Info given:
 Solute = AgNO
3
= 170 g/mol, molar mass
 Volume = 500 mL; must be converted to
Liters.
 Molarity = 2.50
1.
We will need to find moles AgNO
3 to grams.
, then convert
2.
Convert volume to liters:
(500 mL) / 1000 = 0.500 L
3.
Use triangle to calculate moles:
Moles = Molarity x Liters = (2.50)(0.500)
= 1.25 mol
4.
Convert moles to grams: (1.25 mol)(170 g/mol)
= 213 g AgNO
3
.
Example 2:
A solution contains 12.25 g of NaOH in 750 mL.
What is the molarity of the solution?
Info asked for:
 Molarity of the solution
Info given:
 Solute = NaOH = 40 g/mol, molar mass
 Volume = 750 mL: must be converted to liters.
1. Convert grams NaOH to moles:
(12.25 g) / (40 g/mol) = 0.306 mol NaOH
2. Convert mL to L: (750 mL) / 1000 = 0.750 L
3. Use the triangle to calculate Molarity:
M = mol / L = 0.306 mol / 0.750 L = 0.41 M
Example 3:
How many moles of solute are contained in 100 mL of a 0.35 M Na
2
SO
4
solution?
Info asked for:
 Moles solute needed (No need to convert to grams this time.)
Info given:
 Solute = Na
2
SO
4
= 142 g/mol, molar mass
 Volume = 100 mL: must be converted to liters.
 Molarity = 0.35 mol/L
1. Convert mL to L: (100 mL) / 1000 = 0.100 L
2. Use the triangle to calculate the moles:
Mole = molarity x liters = (0.35)(0.100)
= 0.035 mol
Example 4:
You want to make a 1.45 M solution of KBr, and you have 2.00 g of KBr to use. How many mL of this solution can be made?
Info asked for:
 Volume in mL needed (we will find Liters and convert to mL)
Info given:
 Solute = KBr = 119 g/mol, molar mass
 Molarity = 1.45 mol/L
 Grams (mass) of KBr = 2.00 g. Needs to be converted to moles.
1. Convert grams of KBr to moles:
2.00 / 119 = 0.017 mol KBr
2. Use the triangle to find Liters:
L = mol / M = 0.017 / 1.45 = 0.012 L
3. Convert L to mL: (0.012)(1000) = 12 mL