3-8.
SOLVING MILLIMOLE PER LITER PROBLEMS
Calculations involving millimole per liter solution are very similar to the
calculations involving simple mole per liter solutions.
a. Example 1. What is the mmol/L concentration of a 0.25 mol/L NaOH
solution?
Solution. Read the problem carefully and determine the desired unit of
concentration.
mmol/L.
Multiply the given mol/L concentration times the appropriate conversion
factor.
0.25 mol
1000 mmol
--------X ------------ = 250 mmol/L
L
mol
b. Example 2. What is the mol/L concentration of a 2000 mmol/L KCl solution?
Solution. Read the problem carefully and determine the desired unit of
concentration.
mol/L.
Multiply the given mmol/L concentration times the appropriate conversion
factor.
2000 mmol
1 mol
------------X ------------ = 2.000 mol/L
L
1000 mmol
c. Example 3. How much NaCl is needed to make 250 mL of a 300 mmol/L
solution?
Solution. Read the problem carefully and determine the desired quantity.
Milligrams of NaCl.
Determine the millimolar weight of the compound.
NaCl
Na
23.0
Cl
+ 35.5
58.5 mg/mmol
Express the desired volume of solution in liters
1L
250 mL X ---------- = 0.250 L
1000 mL
MD0837
3-8