1. Bellwork Tuesday Today we are learning about solutions.
-What does it mean to dissolve? Be ready to describe it.
-Think of what the word solvent means.

2. 15.2 Aqueous Solutions
Part 2

3. Solutions
Aqueous solution – a water solution containing dissolved substances
Solvent – the dissolving medium
Solute – particles dissolved in the solution
Would the salt or the water be the solute in a salt-water solution?
Salt

4. Question!
Would the salt or the water be the solute in a salt-water solution?

5. Solutions
Solvation – the process that occurs when a solute dissolves in a solvent
EXAMPLE:
Liquid water is constantly in motion, particle collisions break up solute into ions

7. Solutions “Like Dissolves Like”
Polar substances dissolve in polar solvents.
H2O: would dissolve things that are polar and ionic
Nonpolar substances dissolve in nonpolar solvents
Gasoline: would dissolve things that are nonpolar like mineral oil.

9. Write “soluble” next to the compounds listed below that would dissolve in water.
Gasoline ______________
Salt ______________
Alcohol ______________
Vegetable oil ______________

10. Solutions
Electrolytes – compounds that conduct an electric current in aqueous solutions or in a molten state
Includes all ionic compounds
Some very polar molecules dissolved in H2O
Electrolytes in gatorade: citric acid, salt, sodium citrate, monopotassium phosphate, sucrose acetate isobutyrate

11. Solutions
Nonelectrolytes – compounds that do not conduct an electric current in either aqueous solutions or the molten state
Molecular compounds- covalent
Organic compounds (carbon containing compounds)
Nonpolar compounds
Cane sugar, rubbing alcohol, not composed of ions H C H H H

13. Solutions Strong electrolytes: Weak electrolytes:
In a strong electrolyte, nearly all the ions dissolve
in aqueous solution
NaOH, HCl and NaCl
Weak electrolytes:
In a weak electrolyte, only very small amounts of ions dissolve in aqueous solution
Distilled H2O, ammonia and
acetic acid

14. Solutions NH3 + H2O → HCl + H2O → NH4+ + OH- H3O+ + Cl-
How electrolytes form:
NH3 + H2O →
HCl + H2O →
NH OH-
H3O+ + Cl-

15. Hydration Water of hydration – water in a crystal
When copper (II) sulfate is dissolved in water and then the water allowed to evaporate, copper (II) sulfate pentahydrate is formed
CuSO4 + 5H2O ↔ CuSO45H2O
Hydrate - compound that contains water of hydration
Dot used to connect formula of compound and # of water molecules per unit
CoCl2 is blue
CoCl2•6H2O is red
Give them words have them predict products/reactants
The picture above shows copper (II) sulfate pentahydrate. Notice the water molecules surrounding the copper molecules.

16. Hydration CoCl2 + 6H2O ↔ CoCl2 6H2O
When cobalt (II) chloride is dissolved in water and then the excess water is allowed to evaporate, cobalt (II) chloride hexahydrate is formed
CoCl H2O
↔ CoCl2 6H2O

17. In the hydrate CuSO4.5H20, how many water molecules would be present in 3 formula units?

18. Naming Hydrates To name a hydrate, use the following:
They are named by giving the name of the salt followed by a prefix that stands for the number of water molecules associated with a formula unit of the salt.
Ex: CuSO4 • 5H2O
copper (II) sulfate
penta
hydrate

19. Calculating the Percent Hydration
Calculate the percent water in CuSO4•5H2O.
Cu 1
S 1
O 9
H 10
Total mass of hydrate: g
Mass H2O:
H 2
O 1
Total mass of H2O: g X 5 = 90.0g
x 63.5 = 63.5
x 32.1 = 32.1
x 16.0 =
x = 10.0 +
x 1.0 = 2.0
x 16.0 = 16.0 +

20. Hydration
Mass H2O
Mass Hydrate
X 100 = % H2O
90g
X 100
= 36.1%
249.6g

21. Question!
A student performs an experiment in which she heats a hydrated compound with a Bunsen burner in a test tube. What changes should she see in the test tube?

22. Compound(high pressure)
H2O(low pressure)
Hydration
Compound(high pressure)
Efflorescence – process in which hydrated compounds lose water to its surroundings.
Occurs when a substance has a vapor pressure higher than that of water
Some hydrated compounds can effloresce and will form anhydrous compounds
In this process the compound loses water

23. Compound(low pressure)
H2O(high pressure)
Hydration
Compound(low pressure)
Deliquescence – process in which anhydrous or somewhat hydrated compounds gain water from the surroundings.
Occurs when the solution formed has a vapor pressure lower than that of the water in the air
Some anhydrous or somewhat hydrated compounds will deliquesce and form hydrated, or more hydrated, compounds
In this process water is gained

24. Hydration
Desiccants – hygroscopic (water absorbing) substances that are used as drying agents.
Small silica gel packets used in electronic merchandise shipping
Sodium hydroxide is a dessicant and becomes a solution quickly (dissolves itself) when exposed to water in the air

25. 15.3 Heterogeneous Aqueous Systems

26. Suspensions
Suspensions – mixtures from which particles settle out upon standing.
Suspensions have particle sizes larger than solutions
Generally the sizes are larger than 100 nm
The particle size in a solution is about 1 nm
Muddy water is a good example

27. Colloids
Colloids – heterogeneous mixtures containing particles that are intermediate in size between solutions and suspensions
Generally the sizes are
between 1 nm and 100 nm
Examples include glues,
gelatin deserts, paint, aerosols
and smoke
Define heterogeneous- 2 substances can be separated
Whipped cream, marshmellows, milk
Appear cloudy maybe even clear if very dilute, will not settle out
Cannot be filtered with paper filters (like coffee filters)

28. Colloids
Tyndall effect - the scattering of light in all directions. Suspensions also exhibit this effect, but solutions do not.
Fog, ever turned on headlights in fog seen everything light up? That is the tyndall effect
H2O constant motion hitting colloid and causing them to move as well
Called brownian because it was discovered by Robert Brown-Scottish Botanist

29. Colloids
Brownian motion – the chaotic movement of colloidal particles. Under a microscope the particles seem to be moving about erratically.

30. Emulsions Emulsion – a colloidal dispersion of liquids in liquids.
Emulsifying agents are used to keep the emulsion stable-so it will not separate.
Soap and detergents are good emulsifying agents
Mayonnaise is an emulsion. Do you know the main ingredients?
How emulsifying agents work- one polar end 1 not polar end
Ex: oil is attracted to non polar end water attracted to polar end
Vinegar, oil, egg yolk

31. Describe the following as solutions, suspensions, colloids or emulsions.
Paint
Italian dressing
Jello
Milk
Tea
Kool-aid

32. Bellwork Monday
A pot of boiling water contains 200.0ml of water. If the pot was heated from 25.0°C to 100.°C, how much heat was added to make the water boil and vaporize? (Hint: the density of water is 1g/ml)