1. Making Solutions

2. Solutions
Solute – Substance being dissolved
Solvent – Substance doing the dissolving
Concentration = Solute/Solvent

3. Concentration Typically Reported As:
Mass/volume mg/mL
0.5 mg/mL DNA
% (mass/volume or volume/volume)
1% agar
Molarity (moles/liter)
1M NaCl

4. Common for making protein or DNA based solutions:
Mass/Volume
Common for making protein or DNA based solutions:
mg/mL, g/L, μg/ μL
________ x ________= ____________
Concentration Volume Amt. Solute
Desired Desired to be Weighed
*May need to convert units of measurement to make math easier

5. Make 100ml of 5mg/ml Albumin Solution
Example
Make 100ml of 5mg/ml Albumin Solution
________ x ________= ____________
Concentration Volume Amt. Solute
Desired Desired to be Weighed
5mg/mL x 100mL = 500 mg
500 mg = 0.5 g (weigh out)
QS to 100 mL

6. % Mass/Volume Solutions
Often, a procedure calls for a solution made by calculating percent.
Add 10 mL of 10% SDS to your cells
How do we make a 10% Solution of anything?
Remember that 1% = 1 gram in 100 mL
10% = 10 g of SDS up to 100 mL with water

7. Convert % value to decimal value
% Mass/Volume Cont.
Need to factor in that the amount of solute is based on there being 100 parts of solution (100%)
Convert % value to decimal value
Move decimal point two places to the left
25% = 0.25 g/mL
50% = 0.5 g/mL
100% = 1 g/mL

8. ________ x ________= ____________ Concentration Volume Amt. Solute
%Mass/Volume
________ x ________= ____________
Concentration Volume Amt. Solute
Desired Desired to be Weighed
(as a decimal value)
To make 100 mL of 3% CuSO4
Convert 3% to 0.03 g/mL
0.03 g x 100 mL = 3g CuSO4
QS to 100 mL

9. Making Molar Solutions
“Molarity” the most commonly used chemical unit of measurement
It is the number of moles of a solute dissolved in a liter of solution
Same procedure as before, but now must factor in the number of moles of solute

10. Making Molar Solutions
What is a “mole”?
A mole of a substance equals the gram-formula mass…
The sum of all of the masses of all of the elements in the formula of a substance
If you count all of the carbon atoms in in one mole of carbon-12, there would be 6.02 x 1023 atoms, and it would weigh 12 grams (atomic weight of carbon is 12)

11. Making Molar Solutions
________ x ______ x _____ = _______
Concentration Volume Molecular Amt. Solute
Desired Desired Weight to be Weighed
(mol/L) (L) (g/mol) (g)

12. Don’t Panic!
The Formula Weight (also referred to as the Molecular Weight) is on the bottle.
Can also find it using the Periodic Table
1 mole of NaCl weighs 58.4 g
A molecule of NaCl weighs 58.4 amu
Na = 23 amu
Cl = 35.4 amu

13. 100 mL of 2M NaCl (convert 100 mL to 0.1 L)
Example
100 mL of 2M NaCl (convert 100 mL to 0.1 L)
________ x ______ x _____ = _______
Concentration Volume Molecular Amt. Solute
Desired Desired Weight to be Weighed
(mol/L ) (L) (g/mol) (g)
2mol/L x 0.1 L x 58.4 g/mol = g
Weigh out g, QS to 100 mL for 2M NaCl

14. Moving the Decimal Point
1000 mg = 1 g 100 mg = 0.1 g 10 mg = 0.01 g 1.25 grams is how many mg? μL is how many mL?
1000 mL = 1 L 100 mL = 0.1 L 10 mL = 0.01 L 1 mL = L 1000 μL = 1 mL 100 μL = 0.1 mL 10 = μL = 0.01 mL 1 μL = mL

15. Frequently we use concentrated stocks
Making Dilutions
Frequently we use concentrated stocks
Easier to make and store
Calculating how much stock solution to use to make a desired dilution:
C1V1 = C2V2
C1 Concentration of the Stock Solution
V1 Volume to use of Stock (Solve for this)
C2 Desired Concentration of diluted Stock
V2 Desired Volume of the diluted Stock

16. Make 1L of 1mg/mL protease solution from a 100 mg/mL Stock C1V1 = C2V2
Example
Make 1L of 1mg/mL protease solution from a 100 mg/mL Stock
C1V1 = C2V2
Convert to Like units: 1 L = 1000 mL
V1 = 1 mg/mL x 1000 mL = 10mL
100 mg/mL
Add 10 mL Stock to 990 mL diluent to bring to 1L