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TOPIC: intro to solutions and Concentration
Do Now:
Classification of Matter
Matter
PureSubstances
Mixtures
HomogeneousMixtures
HeterogeneousMixtures
Elements Compounds
VIDEO
Solution = (aq)
Homogeneous mixture of 2 or more substances in a single physical state (phase)
Parts of a Solution
• Solute = dissolved substance
• Solvent = dispersing medium (often water)
Solutions occur in all 3 phases!
Alloys: Brass, etc.SolidSolid
Fillings: Hg in AgSolidLiquidH2 in Pd metalSolidGas
Salt waterLiquidSolid
Antifreeze in radiatorLiquidLiquid
Seltzer WaterLiquidGas
MothballsGasSolid
Water Vapor in AirGasLiquid
AirGasGas
ExampleSolventSolute
Gas in a liquid:CO2 in and out of water
Bubbles mean it’s a heterogeneous mixture not a solution!
How can you tell a gas is in a liquid??!?
Alloys
AlloysSolid in solid
We can determine how much solute and solvent make up a solution = CONCENTRATION
Concentration = A measurement that describes how much solute is in a given amount of solvent or solution.
Many, many different units to express concentration. • Molarity• PPM (parts per million)• % by mass• % by volume
Molarity (M)
Molarity (M) = moles of solute
liters of solution
0.1 M HCl : molarity = 0.1M
1M NaSO4: molarity = 1M
So why do aqueous solutions need .1M or 3M
in front?!?!?!
VS
For M, you need moles, so sometimes you’ll have to convert grams to moles
moles
grams
1 mol
FM g
FM g
1 mol
FM = formula mass
Ex: Na3PO4
Na = 3 x 23 = 69P = 1 x 31 = 31O = 4 x 16 = 64
164g/mol
• Sometimes give mL of solution instead of Liters
Milliliters must be converted to liters• Sometimes ask for:
– moles/volume of solute rather than molarity– SO How do you manipulate this equation?
–NOTE: 1 g = 1 ml of water
M = mol L
L = mol M
mol = M L
M Lmol
Practice before you start p.16-171. What is the formula mass ofa. KNO3
2. Convert to molesa. 58g NaCl
3. Convert to L a. 500mlb. 10ml
4. Convert to gramsa. 1000ml
b. 1L
c. 50ml
---------------101 g/mol
---1 mol
--0.5L---0.01L
---1000g
---1000ml = 1000g
---50g
Percent
• By mass
mass (solute) x 100%
mass (solution)
• By volume
volume (solute) x 100%
volume (solution)
• Mass solution = Mass solute + Mass solvent