P. Sci.

Unit 11Unit 11Solutions, Acids and Solutions, Acids and

BasesBasesChapter 8Chapter 8

Solutions

Solutions

• Solution – a mixture that has the Solution – a mixture that has the same composition same composition throughout the throughout the mix.mix.

•Remember the difference Remember the difference between a mixture and a between a mixture and a compound.compound.

Parts of a Solution• Solute – what is Solute – what is

dissolved.dissolved.

• Solvent – what the Solvent – what the solute is dissolved in. solute is dissolved in.

In lesser quantity

In greater quantity

• Solubility – The maximum amount Solubility – The maximum amount of solute that can be dissolved in of solute that can be dissolved in the solvent at a given temperaturethe solvent at a given temperature

Types of Solutions• Saturated solutionsSaturated solutions – max. amount – max. amount

of solute at a given temperature. of solute at a given temperature.

• Unsaturated solutionsUnsaturated solutions – less than the – less than the max. amount of solute at a given max. amount of solute at a given temperature.temperature.

• Supersaturated solutionsSupersaturated solutions – more – more than the max amount of solute at than the max amount of solute at a given temperature; unstablea given temperature; unstable

Concentration• A concentrated solution has a large A concentrated solution has a large

amount of solute in the solvent. amount of solute in the solvent.

• A dilute solution has a small amount of A dilute solution has a small amount of solute in the solvent.solute in the solvent.

•Concentrations can be expressed Concentrations can be expressed as percent by volume of the as percent by volume of the solute example: fruit drinks solute example: fruit drinks contain 10% juice the rest is contain 10% juice the rest is water.water.

The Dissolving Process1)1) Water molecules are polar – they Water molecules are polar – they

have a positive area and a negative have a positive area and a negative area. area.

2)2) Remember, according to the kinetic Remember, according to the kinetic theory, the water molecules are theory, the water molecules are always moving.always moving.

3)3) Water molecules cluster around Water molecules cluster around solid molecules, with their solid molecules, with their negative ends attracted to the negative ends attracted to the positive ends of the solids. positive ends of the solids. . .

4)4) Water molecules pull the solid Water molecules pull the solid particles away from the rest of the particles away from the rest of the solute.solute.

5)5) The moving water molecules and The moving water molecules and solid molecules spread out and mix solid molecules spread out and mix evenly to form a solution. evenly to form a solution. ..

Dissociation – the process in which an ionic Dissociation – the process in which an ionic compound separates into ions as it compound separates into ions as it dissolves.dissolves.

Dispersion – the process in which a molecular Dispersion – the process in which a molecular compound (covalent compound) separates compound (covalent compound) separates into ions as it dissolves.into ions as it dissolves.

Rate of Dissolving• How fast a solute dissolves How fast a solute dissolves

can be affected by:can be affected by:

A.A. Temperature – increasing Temperature – increasing the temperature of a solvent the temperature of a solvent speeds up the movement of speeds up the movement of its particles and therefore its particles and therefore the rate of dissolving.the rate of dissolving.

B.B. Crystal size – dissolving occurs Crystal size – dissolving occurs at the surface of a solid – at the surface of a solid – breaking a solid into pieces or breaking a solid into pieces or powder increases its surface area, powder increases its surface area, which speeds up dissolving.which speeds up dissolving.

C.C. Stirring – speeds up dissolving Stirring – speeds up dissolving by bringing more fresh solvent by bringing more fresh solvent into contact with more solute.into contact with more solute.

Rate of Dissolving

To increase rate of dissolving –To increase rate of dissolving –

• Heat itHeat it

• Crush itCrush it

• Stir itStir it

• To make a gas dissolve more To make a gas dissolve more quickly in a liquid, cool the liquid quickly in a liquid, cool the liquid solvent and increase the pressure solvent and increase the pressure of the gas.of the gas.

“Like dissolves Like”• Polar molecules Polar molecules ((charges uneven charges uneven

so there is a slightly positive end so there is a slightly positive end and a slightly negative endand a slightly negative end)) will will dissolve polar solutes.dissolve polar solutes.

• Non-polar molecules Non-polar molecules ((have no have no charged endscharged ends)) dissolve non-polar dissolve non-polar molecules. molecules.

• Soap is used for washing because it Soap is used for washing because it has polar and non-polar properties. has polar and non-polar properties. The non-polar end grabs the dirt The non-polar end grabs the dirt and oil – the polar end grabs the and oil – the polar end grabs the water so it washes away.water so it washes away.

Solubility Charts / GraphsSolubility of Compounds in g/100g of Water at various Temperatures

Compound 0◦ C 20◦ C 60◦ C 100◦ C

Ammonium chloride 29.4 37.2 55.3 77.3

Copper(II) sulfate 23.1 32.0 61.8 114

Lead(II)chloride 0.67 1.0 1.94 3.2

Potassium bromide 53.6 65.3 85.5 104

Potassium chloride 28.0 34.0 45.8 56.3

Sodium acetate 36.2 46.4 139 170.15

Sodium chlorate 79.6 95.9 137 204

• ChartChart

1)1) How would you classify a solution of 65.3g How would you classify a solution of 65.3g of potassium bromide at 20ºC? ___ of potassium bromide at 20ºC? ___

2)2) How would you classify a solution of 65.3g How would you classify a solution of 65.3g of potassium bromide at 60ºC? ____of potassium bromide at 60ºC? ____

3)3) How would you classify a solution of 65.3g How would you classify a solution of 65.3g of potassium bromide at 0ºC? ____of potassium bromide at 0ºC? ____

4)4) How would you classify a solution of 30g of How would you classify a solution of 30g of KCl at 20ºC? ____KCl at 20ºC? ____

5)5) How would you classify a solution of 37g of How would you classify a solution of 37g of ammonium chloride at 20ºC? _____ammonium chloride at 20ºC? _____

Answer Questions on your paper

• GraphGraph

6)6) How would you classify a solution of 80g of How would you classify a solution of 80g of calcium chloride at 20ºC? ________calcium chloride at 20ºC? ________

7)7) How would you classify a solution of 30g of How would you classify a solution of 30g of KNO3 at 20ºC? ______KNO3 at 20ºC? ______

8)8) How would you classify a solution of 30g of How would you classify a solution of 30g of sodium chloride at 50ºC? ____sodium chloride at 50ºC? ____

9)9) How would you classify a solution of 80g of How would you classify a solution of 80g of sodium nitrate at 30ºC? ____sodium nitrate at 30ºC? ____

10)10)How would you classify a solution of 40g How would you classify a solution of 40g of KClO3 at 80ºC? ____of KClO3 at 80ºC? ____

11)11)How many grams of solute would you How many grams of solute would you need to form a saturated solution of need to form a saturated solution of K2Cr2O7 at 50ºC? ___K2Cr2O7 at 50ºC? ___

12)12)How would you classify a solution of 30g How would you classify a solution of 30g of potassium chloride at 0ºC? ____of potassium chloride at 0ºC? ____

13)13)How much sodium nitrate would you need How much sodium nitrate would you need to form a saturated solution at 10ºC? ____to form a saturated solution at 10ºC? ____

14)14)How would you classify a solution of 50g How would you classify a solution of 50g of potassium chloride at 50ºC? ______of potassium chloride at 50ºC? ______

15)15)Which salt decreases in solubility as the Which salt decreases in solubility as the temperature increases? _____temperature increases? _____