TOPIC: intro to solutions and Concentration

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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