1. I. The Nature of Solutions
Ch. 13- Solutions

2. Solution – homogeneous mixture
Solute - substance being dissolved
Solvent – does the dissolving - present in greater amount

3. Aqueous – dissolved in water Tincture – dissolved in alcohol
Solute - KMnO4
Solvent - H2O

4. Solvation – the process of dissolving
solute particles are surrounded by solvent particles
First...
solute particles are separated and pulled into solution
Then...

5. Solutions form faster if …
The temp is increased. (mostly)
2) The surface area is increased.
3) The solution is agitated.
WHY?

6. Alloy – a metal solution
Ex. Cu & Zn = brass
Cu & Sn = bronze
Miscible – 2 gases or 2 liquids dissolved in each other (immiscible = not dissolved)

7. Solvation Non- Electrolyte Weak Electrolyte Strong Electrolyte+
sugar - +
acetic acid - +
salt
Non-
Electrolyte
Weak
Electrolyte
Strong
Electrolyte
solute exists as
molecules only
solute exists as
ions and
molecules
solute exists as
ions only
DISSOCIATION
IONIZATION
View animation online.

8. How do you know if a solute will dissolve?
“Like Dissolves Like”
NONPOLAR
POLAR

9. What about soap? Soap/Detergent polar “head” with long nonpolar “tail”
dissolves nonpolar grease in polar water

10. Solutions UNSATURATED SOLUTION more solute dissolves
no more solute dissolves
SUPERSATURATED SOLUTION
becomes unstable, crystals form
concentration

11. Solubility Solubility
maximum grams of solute that will dissolve in 100 g of solvent at a given temperature
varies with temp
based on a saturated soln

12. Solubility Solubility Curve
shows the dependence of solubility on temperature

13. Solubility Solids are more soluble at... Gases are more soluble at...
high temperatures.
Gases are more soluble at...
low temperatures &
high pressures (Henry’s Law). (coke)
EX: nitrogen narcosis, the “bends,”

14. Can it be physically separated?
Matter Flowchart
MATTER
yes no
Can it be physically separated?
MIXTURE
PURE SUBSTANCE
Is the composition uniform? no
yes
Can it be chemically decomposed? no
yes
Homogeneous Mixture
(solution)
Heterogeneous Mixture
Compound
Element
Colloids
Suspensions

15. Mixtures 1) Solution particles don’t settle homogeneous
very small particles
no Tyndall effect
Tyndall Effect
particles don’t settle
EX: rubbing alcohol

16. Mixtures 2) Colloid heterogeneous medium-sized particles
Tyndall effect
particles don’t settle
EX: glues, paint, milk

17. Mixtures 3) Suspension heterogeneous large particles Tyndall effect
particles settle
filterable
EX: fresh-squeezed lemonade

18. Mixtures Examples: colloid mayonnaise suspension muddy water fog
solution
Examples:
mayonnaise
muddy water
fog
saltwater
Italian salad dressing

19. Concentration The amount of solute in a solution. (how strong)
Describing Concentration
% by mass - medicated creams
% by volume - rubbing alcohol
ppm, ppb - water contaminants
molarity - used by chemists
molality - used by chemists

20. Molality m =moles/kg Molality = moles of solute kg of solvent
Mass of solvent only
For water:
1kg =1000ml

21. Molarity - most important
The # of moles solute in 1 L of the solution.
M = moles (as in 6.0 molar or 6M)
liter
What is the molarity of a solution with 2.0 moles of NaCl in 250 mL of solution?

22. To make a solution Pour in a small amount of solvent
Then add the solute (to dissolve it)
Carefully fill to final volume.
Also: M x L = moles
How many grams of NaCl are needed to make 6.0 L of a 0.75 M NaCl solution?

23. Making solutions
10.3 g of NaCl are dissolved in a small amount of water, then diluted to 250 mL. What is the concentration?
How many grams of glucose are needed to make 125 mL of a 0.50 M C6H12O6 solution?

24. Dilution
The number of moles of solute doesn’t change if you add more solvent!
The # moles before = the # moles after
M1 x V1 = M2 x V2
M1 and V1 are the starting concentration and volume.
M2 and V2 are the final concentration and volume.
Stock solutions are pre-made to known Molarity

25. Percent solutions... Percent means parts per 100, so
Percent by volume: = Volume of solute x 100% Volume of solution
indicated %(v/v)
What is the percent solution if 25 mL of CH3OH is diluted to 150 mL with water?

26. Percent solutions
Percent by mass: = Mass of solute(g) x 100% Volume of solution(mL)
Indicated %(m/v)
More commonly used
4.8 g of NaCl are dissolved in 82 mL of solution. What is the percent of the solution?
How many grams of salt are there in 52 mL of a 6.3 % solution?

27. B. Molality
mass of solvent only
1 kg water = 1 L water

28. C. Dilution
Preparation of a desired solution by adding water to a concentrate.
Moles of solute remain the same.

29. D. Preparing Solutions 1.54m NaCl in 0.500 kg of water
500 mL of 1.54M NaCl
mass 45.0 g of NaCl
add water until total volume is 500 mL
mass 45.0 g of NaCl
add kg of water
500 mL water
45.0 g NaCl
500 mL
mark
volumetric
flask

30. D. Preparing Solutions
Copyright © NT Curriculum Project, UW-Madison
(above: “Filling the volumetric flask”)

31. D. Preparing Solutions 250 mL of 6.0M HNO3 by dilution
measure 95 mL of 15.8M HNO3
95 mL of 15.8M HNO3
combine with water until total volume is 250 mL
250 mL mark
Safety: “Do as you oughtta, add the acid to the watta!”
water for safety