BELLWORK1. Which factors determine how much a solute

dissolves in a given solvent?2. Which factors affect the rate of dissolution?

3. How is solubility measured?4. Define saturated and unsaturated

When salts dissolve in water, positiveand negative ions are separated andsurrounded by polar water molecules.

Concentration measures how muchsolute is in a solution

High Low Concentration Concentration

diluteconcentrated

Chemists need to quantify concentration

WE NEED NUMBERS!!!

Concentrated

Exactly how much solute is in the solution?

What units could we use to quantify theamount of solute?

Grams, moles, liters,teaspoons, number of ions

Is the amount of solute enough info to measurethe concentration?

1 gram of salt.

In 10mL or in 10L?We must specify the amount of solvent as well

Concentration is

the amount of solute the amount of solution

solute .

total solution

Concentration can be measured in many units

Concentration can be measured in many units

Grams/Liter

Percent concentration by volume %(v/v)

Percent concentrationby mass %(w/w)

Parts per million ppm

Molarity M

Grams/Liter

A solution with a concentration of0.75g/L contains 0.75g of solute inevery 1 liter

How much solute is in 6.2L of thesolution?

6.2 L x 0.75g/L = 4.65grams

Grams/Liter

A solution has a concentration of 0.75g/L

How much solute is in 250mL of thesolution?

How much solution contains 10g of solute?

0.25L x 0.75g/L = 0.19grams

10g x 1L = 13.33L 0.75g

Percent concentration by volume %(v/v)

Hydrogen peroxide solutions are 3% H2O2by volume. How much H2O2 is in a 500mLbottle? How much water?

%(v/v) = volume of solute volume of solution

x 100%

500mL x 0.03 = 15mL

500ml solution – 15ml solute = 485ml solvent

Percent concentrationby mass %(w/w)

%(w/w) = mass of solute mass of solution

x 100%

Determine the mass % of a NaCl solution if58.5 grams of NaCl was dissolved in 50 mlof water (assume the density of water tobe 1 g/ml)

Determine the mass % of a NaCl solution if 58.5grams of NaCl was dissolved in 50 ml of water(assume the density of water to be 1 g/ml)

1. Convert ml of water to gramsmass = 50 ml X 1 g/ml = 50 grams water

2. Determine total mass of solutionMass of solution = mass of solute + mass of solvent

= 58.5 + 50 = 108.5 g3. Apply the definition of mass percent

mass % = 58.5/ 108.5 x 100%= 53.9% NaCl

Parts per million ppm

Parts per million or ppm is used forvery dilute (weak) solutions. It is likepercent, except it is permillion!

ppm = grams solute grams of solution

x 106

Do #6 from worksheet

And the one used most in chemistry

Molarity M

Molarity = moles/liter

2M HCl contains2 moles of HCl in every liter.

How many moles are in 56mL of 2M HCl?

.056L x 2moles/L = 0.112moles HCl

M = moles/Liter

M x V = moles

moles/liter x liters = moles

Making a solution of knownconcentration

Do #9a

Making DilutionsDilution = Adding more solvent to a solutionMolarity = Moles Liter

16.2

Doesn’t change

increases

DilutiondecreasesconcentrationMaking thesolutionMOREDILUTE!!

M1 and V1 are the molarity and volume of theinitial solutionM2 and V2 are the molarity and volume of the

diluted solution.

16.2 Making Dilutions

How much 10M HCl is needed tomake 200mL of a 0.5M solution?

10M x V1 = 0.5M x .2L add 0.01L or 10ml