Tube 1
Tube 2
Tube 3
Tube 4
Chlorella/Euglena
2 mL
2 mL
2 mL
2 mL
Spring Water
1 mL
1 mL
1 mL
1 mL
(Name and Concentration
of Chemical stock solution
used___10%_______)
__mL
__mL
__mL
__mL
Spring Water
__mL
__mL
__mL
__mL
Total Volume
5 mL
5 mL
5 mL
5 mL
[X] Chemical
Final Concentration of
Chemical in Test Tube
TO CALCULATE DILUTIONS OF CHEMICALS USE THIS FORMULA:
Number of mLs of Stock Solution
Total Volume of Dilution
[Concentration
of Stock Solution]
X
=
Final Concentration of
Chemical in Test Tube
For example:
HOW WOULD YOU PREPARE A 2% NACL SOLUTION FROM A 10% NACL STOCK
SOLUTION?
STEP 1: WE KNOW: Total volume of solution is 5 mL
Concentration of Stock solution is 10%
Final Concentration of Chemical desired is 2%
WE DON’T KNOW: The number of mL of Stock solution we need to prepare
this dilution (let X represent this value).
STEP 2: PLUG IN THE NUMBERS YOU KNOW INTO THE EQUATION AND SOLVE
FOR X:
X
5
10
*
=
2
STEP 3: SOLVE FOR X:
X
=
1
(remember, the units are in mLs)
STEP 4: PUT IT ALL TOGETHER:
To make 5 mL of a 2% solution from a 10% stock solution, mix 1 mL of 10% NaCl stock
solution plus 2 mL of sterile water for a volume of 3mL. When this chemical dilution is
added to the 2 mL of Chlorella solution, it will bring the total volume to 5 mL and further
dilute the NaCl to a final concentration of 2%.