P. Sci. Unit 11 Solutions, Acids and Bases Chapter 8

Solutions

Solution – a mixture that has the same composition throughout the mix.Solution – a mixture that has the same composition throughout the mix. Remember the difference between a mixture and a compound.Remember the difference between a mixture and a compound.

Parts of a Solution Solute – what is dissolved.Solute – what is dissolved. Solvent – what the solute is dissolved in.Solvent – what the solute is dissolved in. In lesser quantity In greater quantity

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

Types of Solutions Saturated solutions – max. amount of solute at a given temperature.Saturated solutions – max. amount of solute at a given temperature. Unsaturated solutions – less than the max. amount of solute at a given temperature.Unsaturated solutions – less than the max. amount of solute at a given temperature.

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

Concentration A concentrated solution has a large amount of solute in the solvent.A concentrated solution has a large amount of solute in the solvent. A dilute solution has a small amount of solute in the solvent.A dilute solution has a small amount of solute in the solvent. Concentrations can be expressed as percent by volume of the solute example: fruit drinks contain 10% juice the rest is water.Concentrations can be expressed as percent by volume of the solute example: fruit drinks contain 10% juice the rest is water.

The Dissolving Process 1)Water molecules are polar – they have a positive area and a negative area. 2)Remember, according to the kinetic theory, the water molecules are always moving.

3)Water molecules cluster around solid molecules, with their negative ends attracted to the positive ends of the solids.. 4)Water molecules pull the solid particles away from the rest of the solute.

5)The moving water molecules and solid molecules spread out and mix evenly to form a solution.. Dissociation – the process in which an ionic compound separates into ions as it dissolves. Dispersion – the process in which a molecular compound (covalent compound) separates into ions as it dissolves.

Rate of Dissolving How fast a solute dissolves can be affected by:How fast a solute dissolves can be affected by: A.Temperature – increasing the temperature of a solvent speeds up the movement of its particles and therefore the rate of dissolving.

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

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

Rate of Dissolving To increase rate of dissolving – Heat itHeat it Crush itCrush it Stir itStir it

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

“Like dissolves Like” Polar molecules ( charges uneven so there is a slightly positive end and a slightly negative end ) will dissolve polar solutes.Polar molecules ( charges uneven so there is a slightly positive end and a slightly negative end ) will dissolve polar solutes. Non-polar molecules ( have no charged ends ) dissolve non-polar molecules.Non-polar molecules ( have no charged ends ) dissolve non-polar molecules.

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

Solubility Charts / Graphs Solubility of Compounds in g/100g of Water at various Temperatures Compound0 ◦ C20 ◦ C60 ◦ C100 ◦ C Ammonium chloride Copper(II) sulfate Lead(II)chloride Potassium bromide Potassium chloride Sodium acetate Sodium chlorate

ChartChart 1)How would you classify a solution of 65.3g of potassium bromide at 20ºC? ___ 2)How would you classify a solution of 65.3g of potassium bromide at 60ºC? ____ 3)How would you classify a solution of 65.3g of potassium bromide at 0ºC? ____ 4)How would you classify a solution of 30g of KCl at 20ºC? ____ 5)How would you classify a solution of 37g of ammonium chloride at 20ºC? _____ Answer Questions on your paper

GraphGraph 6)How would you classify a solution of 80g of calcium chloride at 20ºC? ________ 7)How would you classify a solution of 30g of KNO3 at 20ºC? ______ 8)How would you classify a solution of 30g of sodium chloride at 50ºC? ____ 9)How would you classify a solution of 80g of sodium nitrate at 30ºC? ____ 10)How would you classify a solution of 40g of KClO3 at 80ºC? ____

11)How many grams of solute would you need to form a saturated solution of K2Cr2O7 at 50ºC? ___ 12)How would you classify a solution of 30g of potassium chloride at 0ºC? ____ 13)How much sodium nitrate would you need to form a saturated solution at 10ºC? ____ 14)How would you classify a solution of 50g of potassium chloride at 50ºC? ______ 15)Which salt decreases in solubility as the temperature increases? _____