1. Chemical Solutions (aqueous = water is the solvent)
Types of vessels (least to most precise):
Beaker
Erlennmeyer flask
Graduated cylinder
Volumetric flask

2. Goals Make solutions Dilute solutions
Convert between different concentrations of solutions

3. Facts of Life Mass is measured in Grams, mg, μg
1g = 1000mg = µg
Volume is measured in liters, mL, μL
1L = 1000mL = μL
Density of water is 1 g / mL

4. Facts of life (cont’d)
Concentration means: amount of solute in a volume of solution
Expressed 3 ways:
1. percent
2. mg/ mL
3. molar

5. Percent Solutions Per means “for every one” Cent means 100
Example: a 5% sugar solution has
5 grams of sugar for 100g of solution

6. Make 250 mL of a 3% starch solution
3 g / 100 g = 3 g / 100 mL because density of water is 1 g / mL
Set up a ratio:
3 g / 100 mL = ?g / 250 mL
Use 7.5 g of starch and bring to a volume of (BTV) 250 mL with water

7. mg / mL Solutions
5 mg/mL has 5 milligrams of solute in 1 milliliter of solution

8. Make a 250 mL of a 3 mg /mL starch solution
Set up a ratio:
3 mg / 1 mL = ?mg / 250 mL
Use 750 mg of starch and bring to a volume of (BTV) 250 mL with water

9. Molar Solutions 1 mole is 6.02 x 1023 items
Molecular weight or Formula weight is really the mass of 1 mole of molecules (see periodic table)
Example: 1 mol of sodium chloride (NaCl) has a mass of g.

10. A 1 Molar solution is 1 mol of solute /Liter of solution
Make 250 mL of a 3 molar NaCl solution
Set up a ratio:
58.44 g /1 mol = ? g / 3 mol
3 moles has a mass of g
3M = 3mol/L = 175.3g/1000mL = ? g/250mL
? = 43.8g
BTV of 250 mL

11. Diluting Solutions Conc A x Vol. A = Conc B x Vol B
Usually want 1 X solutions

12. Example: Frozen Orange Juice
Solution A is the frozen concentrate
Solution B is the 1X juice you drink
How concentrated is it?
CA VA = CB VB
(250mL)(?X) = (1000 mL)(1X)

13. Answer: Frozen OJ is 4X because ¼ of the final volume is the concentrated oj