SOLUTIONS

SOLUTIONSHomogeneous mixture containing two or more substance called the solute and the solvent.SOLUTE: Substance

that is dissolved (lower quantity).

SOLVENT: Dissolving medium (higher

quantity).

TYPES OF SOLUTIONS

•SOLUBLE: Substance that dissolve in a solvent (sugar or salt)

•INSOLUBLE: Substance that do not dissolve in solvent oil or sand

•INMISIBLE: Both liquids and can not be mixed

•MISIBLE: Both liquids and can be mixed

SOLVATIONThe process of surrounding solute particles with solvent particles in water is called solvation.

Temperature agitation and more quantity of solute can raise the rate of solubility.

SOLUBILITYMaximum amount of solute that will dissolved in a given amount of solvent at a specified temperature and pressure.Solubility is usually expressed in grams of solute per 100 grams of solvent.

Saturated solutionUnsaturated solutionSupersaturated solution

SOLUTION CONCENTRATION

CONCENTRATION.- Measure of how much solute is dissolved in a specific amount of solvent or solution.

Qualitative Dilute

Concentrate

SOLUTION CONCENTRATION•Quantitative

Percent by mass mass solute X 100 mass solution

Percent by volume Volume solute X100 Volume solution

Molarity Mol of solute Liter of solution

Molality Moles of solute Kg of solvent

Mole fraction Moles of solute Moles of solute + moles of solvent

PERCENT BY MASS• The percent by mass is the ratio of the solute’s

mass to the solution’s mass expressed as a percent. The mass of the solution equals the sum of the masses of the solute and the solvent.

Usually describes a solid dissolved in a liquid!

EXAMPLE: Percent by massIn order to maintain a sodium chloride (NaCl)

concentration similar to ocean water, an aquarium most contain 3.6 g NaCl per 100 g of water. What is the percent by mass of NaCl in the solution?

CLASSWORK

•Solve problems 8, 9 and 10 of Practice Problems page 463.

PERCENT BY VOLUME• Is the ratio of the volume of the solute to the volume

of the solution expressed as a percent. The volume of the solution is the sum of the volumes of the solute and the solvent.

Usually describes a liquid dissolved in a liquid!

EXAMPLE: Percent by volumeWhat is the percent by volume of ethanol in a

solution that contains 35 ml of ethanol, dissolved in 115 ml of water?

CLASSWORK

•Solve problems 11, 12 and 13 of Practice problems page 464.

MOLARITY..•Is the number of moles of solute dissolved

per liter of solution. Also known as molar concentration.

1L

1 mol

1 mol

EXAMPLE: Molarity

Calculate molarity of 100 ml of aqueous solution containing 0.085 moles of dissolved potassium chloride KCl.

CLASSWORK

Solve problems 14, 15 16 of Practice problems page 465.

MOLALITY•Is the ratio of the number of moles of

solute dissolved in one kilogram of solvent.

1 mol

1 mol

1 kg

Molality In the lab a student add 4.5 moles of sodium

chloride NaCl to 100 g of water. Calculate the molality of the solution.

CLASSWORK

•Solve problems 24 and 25 of Practice Problems page 469.

MOLE FRACTION•Is the ratio of the number of moles of

solute in solution to the total number of moles of solute and solvent.

Where nA is the number of moles of solute and nB the

number of moles of solvent.

1 mol A

1 mol A

Mol of B

Mole fraction Calculate the mole fraction of hydrochloric acid

HCl in the aqueous solution. For every 100 g of solution, 37.5 g would be HCl and 62.5 g would be the water.

CLASSWORK

•Solve problems 26 and 27 of Practice problems page 470.

pH

Is a measure of the acidity or basicity of a solution. It is defined as the cologarithm of the activity of dissolved hydrogen ions (H+).

The pH scale is not an absolute scale; it is relative to a set of standard solutions whose pH is established by international agreement

[H3O+] moles/liter

pH p0H

100=1 0 14 Very acidic

10-1 1 13

10-2 2 12

10-3 3 11

10-4 4 10

10-5 5 9 Weakly acidic

10-6 6 8

10-7 7 7 Neutral

10-8 8 6

10-9 9 5 Weakly basic

10-10 10 4

10-11 11 3

10-12 12 2

10-13 13 1

10-14 14 0 Very basic

Formulas

pH= -log [H+]pOH= -log [OH-]pH+POH= 14

Practice problemsThe concentration of either the H+ ion or the OH- ion is given, calculate [H+ ] and te or [OH-]. State whether the solution is acidic, basic, or neutral.a) [H+ ]= 1.0 X 10-13 M b) [OH- ]= 1.0 X 10-7 M c) [OH- ]= 1.0 X 10-3 M

HOMEWORK