Solutions
ch 13-14 p. 394
Solution: one substance dissolved into another substance
3 types:
gas…..
liquid…
solid….
2 parts: solute = substance being dissolved……’smaller part’
solvent = substance doing the dissolving …’larger part’
Ex:
salt water
carbonated pepsi
Kool-aid
Heterogeneous = a visible mixture of 2 or more
Homogenous = one kind
lemonade
How to speed up dissolving?
l. Stir
2. Increase surface area….
grind large chunks into small grains
3. change temperature of solvent
a. increase temp…..sugar in tea
b. Decrease temp…..gas in pepsi
Why are GASES ARE MORE SOLUBLE IN COOLER
SOLVENTS
How do the methods of
speeding the rate of solution for
dissolving a solid in a liquid
compare to the methods of
speeding the rate of solution for
dissolving a gas in a liquid?
Determining what will dissolve?
How do things dissolve?
Water is considered the universal solvent… water is a polar
molecule with + and – ends. The positive end of a polar
molecule will attract the negative end of another polar
molecular. Hence….
” like dissolves like”.
“polar dissolves polar”
“Nonpolar dissolves nonpolar”
Polar means having opposite ends, which means one end of
the molecule is positive and the other end is negative.
“like dissolves like” explains why
salt dissolves in water (both are polar)
any ionic (m+nm) will dissolve in water
Like dissolves like explains why
salt does not dissolve in ethanol
one is polar the other is nonpolar
“water and oil” --- polar and non polar --- doesn’t mix
Overhead 73
How does one figure
if polar or non polar ????
1. all ionics are polar …. Metal + nonmetal
2. draw lewis structures
3. calculate electronegativity
1.7
Solute
NaCl
I2
Br2
KNO3
Ca(OH)2
CF4
HCl
H2SO4
Cu2SO4
Fe(NO3)
Water
CCl4
-
-
Electrolyte: a solution that can conduct electricity
ex: ionic solutions
ionic compounds …
ionizes into their separate ions when dissolved in water.
“They separate into their + and - parts.”)
Non electrolyte: a solution that can not conduct electricity
ex: nonpolar solutions
non-metals and non-metals do not have + or - ends
Demo: salt in water
Solute
NaCl
I2
Br2
KNO3
Ca(OH)2
CF4
HCl
H2SO4
Cu2SO4
Fe(NO3)
electrolyte
non-
-
-
Solubility
how much will dissolve at a given temperature.
Unsaturated: can dissolve more solute
Saturated: dissolved all it can
Supersaturated: contains more solute
than a saturated . ”unstable”
Reading solubility curve….ws 13.22 , 13.12
[concentration] of Solutions
p.412 Expressed as …..Molarity
[M] = #moles of solute
liters of solution
As a chemist you need to solve the following solutions for an experiment.
1. What is the molarity of a solution consisting of 45
grams of Sodium Chloride in 500mL of water?
2. A chemist needs half a liter of a [2M] solution of
ammonia. How do you prepare it?
3. Calculate the concentration of a sodium
hydroxide solution containing 10.0 grams
in 500mL.
4. What is the molarity of a sulfuric acid
solution containing 196 grams per liter?
Quick Lab
• Prepare 100mL of a .5M Sodium
Hydroxide solution.
• Label with you name and store upright in
bottom drawer.
Molarity by Dilution
M1V1 = M2V2
You use this when you already have a solution made and you just want to
dilute it to the concentration you want.
1. How much concentrated 12M Hydrochloric acid is
needed to prepare 300 mL of a 3.0 M solution?
2. How much water should be added to
200mL of 18M Sulfuric acid to have a
l.5M solution?
3. How much of concentrated 15M Nitric
acid should be added to make a 1 liter
solution of 2M.
4. To how much water should 50.mL of 12 M
hydrochloric acid be added to produce a
4.0 M solution?
Flip side of ws.
• stop