SOLUTIONS A homogeneous mixture in which the components are uniformly intermingled.

SOLUTIONS

A homogeneous mixture in which the components are uniformly intermingled

Terms

Solvent – The substance present in the largest amount in a solution. The substance that does the dissolving.

Solute – The other substance or substances in a solution. The substance that is dissolved.

ELECTROLYTES

Substances that break up in water to produce ions.

These ions can conduct electric current Examples: Acids, Bases and Salts (ionic

compounds)

SOLUBILITY

“Like dissolves Like”– Polar molecules dissolve polar molecules – Nonpolar molecules dissolve nonpolar molecules

SOLUBILITY RULES

All common salts of Group I elements and ammonium are soluble

All common acetates and nitrates are soluble All binary compounds of Group 7 with metals are

soluble except those of silver, mercury I and lead All sulfates are soluble except those of barium,

strontium, calcium, silver, mercury I and lead Except for those in Rule 1, carbonates, hydroxides,

oxides, sulfides and phosphates are insoluble

Terms

Saturated – When a solution contains the maximum amount of solute

Unsaturated – When a solvent can dissolve more solute

Supersaturated – When the solution contains more solute than a saturated

solution will hold at that temperature Concentrated

– When a relatively large amount of solute is dissolved Dilute

– When a relatively small amount of solute is dissolved

Factors Affecting the Rate of Dissolution

Surface Area

Stirring

Temperature

Temperature vs Solubility

MOLARITY

Molarity-the number of moles of solute per liters of solution

M = molarity = moles of solute

liter of solution

Calculate the molarity of a solution prepared by dissolving 11.5 g of NaOH in enough water to make a 1.50 L solution.

Calculate the molarity of a solution prepared by dissolving 1.56 g of HCl into enough water to make 26.8 ml of solution.

Calculate the number of grams of sodium phosphate required to make 150. ml of a 2.5M solution.

How many liters of solution are needed to dissolve 5.0 g of hydrochloric acid to make a 3.0 M hydrochloric acid solution?

What is the concentration of each ion in a 0.50 M solution of Co(NO3)2?

What is the concentration of each ion in a 0.25 M solution of aluminum sulfate?

How many moles of Ag+ ions are present in 25.0 ml of a 0.75 M AgNO3 solution?

Calculate the number of moles of Cl- ions in 1.75 L of 1.0 x 10-3M AlCl3

To analyze the alcohol content of a certain wine, a chemist needs 1.00 L of an aqueous 0.200 M K2Cr2O7 (molar mass is 294.2g/mol) How much K2Cr2O7 must be weighed out to make this solution?

DILUTIONS

M1 x V1 = M2 x V2

What volume of 16 M sulfuric acid must be used to prepare 1.5 L of a 0.10 M H2SO4

What volume of 12 M HCl must be used to prepare 0.75 L of a 0.25 M HCl?

When barium nitrate and potassium chromate react in aqueous solution, the yellow solid barium chromate is formed. Calculate the mass of barium chromate that forms when 3.50 x 10-3 mole of solid barium nitrate is dissolved in 265 ml of 0.0100 M potassium chromate solution.

MOLALITY

A unit of concentration equal to the number of moles of solute per kilogram of solvent

m = moles of solute

kg solvent

98.0 g RbBr in 824 g water

85.2 g SnBr2 in 1.40 x 102 g water

Phase Change Diagram

Definition

Boiling Point – when the vapor pressure of the liquid is equal to the atmospheric pressure

Freezing Point Depression/Boiling Point Elevation

Colligative property – a solution property that depends on the number of solute particles present (ie – f.p. and b.p.)– Freezing Point Depression

– Boiling Point Elevation

Calculating Boiling Points

Kbp = boiling point constant– Water 0.515OCkg/mol– 1 mole of a solute particle will raise the bp of 1 kg of water

by 0.515OC 1m solution of sugar water

1(0.515OC)

100.515OC 1m solution of NaCl water

2(0.515OC)

101.03OC 1m solution of CaCl2 water

3(0.515OC)

101.545OC

Calculating Freezing Points

Kfp = freezing point constant– Water 1.853OCkg/mol– 1 mole of a solute particle will lower the fp of 1 kg of water

by 1.853OC 1m solution of sugar water

1(1.853OC) -1.853OC

1m solution of NaCl water 2(1.853OC) -3.706OC

1m solution of CaCl2 water 3(1.853OC) -5.559OC

ΔTfp = im Kfp ΔTbp = im Kbp

Kfp = 1.853oCkg/mol Kbp = 0.515oCkg/mol

If 26.4 grams of nickel II bromide are dissolved in 224 grams of water, what will be the new boiling point and freezing point of the resulting solution?

If 25.0 grams of calcium chloride are dissolved in 500 grams of water, what will be the new boiling point and freezing point of the resulting solution?

MASS PERCENT

A unit of concentration equal to the mass of solute per mass of solution

part x 100

whole

A solution is prepared by mixing 1.00 g of ethanol with 100.0 g of water. Calculate the mass percent of ethanol in this solution.

A 135 g sample of seawater is evaporated to dryness, leaving 4.73 g of salt. Calculate the mass percent of salt in the saltwater.

1.Molarity (M) =

2.Mass (weight) percent =

3.Mole fraction (A) =

4.Molality (m) =

moles of soluteliters of solution

mass of solutemass of solution

100%

molestotal moles in solution

A

moles of solutekilograms of solvent

Sol’n is prepared by adding 5.84 g of formaldehyde (H2CO) to 100.0 g water. Final vol of solution is 104.0 mL. Calculate the molarity, molality, mass % and .

M = 1.87 M H2COm = 1.94 m H2COMass %= 5.52 % H2CO = .0338

Molecular Mass Determination

If 99.0 g of a nonionizing solute dissolved in 669 grams of water and the freezing point of the resulting solution is -0.960oC, what is the molecular mass of the solute?

ΔTfp = im Kfp m = ΔTfp

Kfp

If 64.3 g of a nonionizing solute dissolved in 390. grams of water and the boiling point of the resulting solution is 100.680oC, what is the molecular mass of the solute?

ΔTbp = im Kbp m = ΔTbp

Kbp

Anthraquinone contains only carbon, hydrogen and oxygen and has an empirical formula of C7H4O. When 15.93g of anthraquinone are added to 1 kg of water the freezing point depression was determined to be 0.240oC. Calculate the molar mass of the biomolecule (Kf for chloroform is 4.70oCkg/mol)