1. “Making solutions with multiple components”
Part II: Making solutions from concentrated stock solutions

2. Often, solutions containing multiple components are prepared from concentrated stock solutions…
Stock solutions vary in their concentrations, and in the units used to express their concentrations, but are all used in the same way…
10X TBE
70% Glycerol
5 M NaCl

3. To prepare solutions for use in the lab, stock solutions are DILUTED to the correct working concentration…
Suppose I need to make 5 L of 0.05 M NaCl from a 5 M NaCl stock solution…
and enough water to make 5 L total solution
I will need to add some volume of 5 M NaCl…
Let’s figure out what volume of NaCl stock we need…
5 L
5 M NaCl

4. What volume of NaCl stock do I add?
Use C1V1 = C2V2
C1 = 5 M
C2 = 0.05 M
V1 = ?
V2 = 5 L = 5000 mL
V1 = (0.05 M)(5000 mL)
5 M
V1 = 50 mL
and enough water to make 5 L total solution
I will need to add 50 mL of 5 M NaCl…
50 mL
5 L
Let’s make the solution…
5 M NaCl

5. Let’s make the solution…
and enough water to make 5 L total solution
I will need to add 50 mL of 5 M NaCl…
5 L
5 M NaCl
0.05 M
NaCl
Done!

6. Now let’s make a solution containing two solutes from concentrated stock solutions…

7. Here is a simple solution containing multiple components:CG
50 mM calcium chloride
15% glycerol
This is ONE solution with multiple components that we will make from the following stock solutions:
1 M CaCl2
60% Glycerol

8. Making 500 mL of CG from concentrated stock solutions…
and enough water to make 500 mL total solution
I will need to add some volume of 1 M CaCl2…
500 mL
and some volume of 60% glycerol
1 M CaCl2
H2O
60% Glycerol
Let’s do the math…

9. What volume of 1 M CaCl2 do I need?
Use C1V1 = C2V2
C1 = 1 M = 1000 mM
C2 = 50 mM
V1 = ?
V2 = 500 mL
V1 = (50 mM)(500 mL)
1000 mM
V1 = 25 mL
and enough water to make 500 mL total solution
500 mL
and some volume of 60% glycerol
I will need to add 25 mL of 1 M CaCl2…
H2O
25 mL
1 M CaCl2
60% Glycerol
Let’s continue…

10. What volume of 60% Glycerol do I need?
Use C1V1 = C2V2
C1 = 60%
C2 = 15%
V1 = ?
V2 = 500 mL
V1 = (15%)(500 mL)
60%
V1 = 125 mL
and enough water to make 500 mL total solution
500 mL
and 125 mL of 60% glycerol
I will need to add 25 mL of 1 M CaCl2…
125 mL
H2O
25 mL
1 M CaCl2
60% Glycerol
Let’s finish…

11. Let’s make our solution…
and 125 mL of 60% glycerol
H2O
I will need to add 25 mL of 1 M CaCl2…
500 mL
…to enough water to make 500 mL total solution
Done! CG