Solubility and Solubility curves Solubility The solubility of a substance is the mass required to make a saturated solution in a given quantity of solvent usually water at a certain temperature Solubility at a given temperature maximum mass g of a substance that will dissolve in 100 ml of water For example at 20 C the solubility of potassium nitrate is 32 g per 100 g of water Solubility of a substance is affected by 1 The nature of the substances For example ionic compounds and hydrates dissolve in aqueous solutions 2 The polarity of the substances For example polar substances dissolve in polar solvents 3 The temperature Some substances only dissolve above certain temperatures 4 The pressure Some substances only dissolve when under pressure Solubility of a solid KClO3 Mass Temp Mass Temp 3 0 30 69 10 28 35 76 15 40 40 83 20 52 45 87 25 60 50 93 Draw a graph of the maximum mass of KClO3 dissolved vs temperature Solubility curve for KClO3 100 g solute10 g 100 mlgH 20 60 50 40 30 20 10 0 0 10 20 30 40 50 60 70 80 90 Temperature C Solubility types Saturated solution a solution containing the maximum quantity of solute at a specific temperature and pressure Unsaturated A solution containing less than the maximum quantity of solute possible for that solvent at a specific temp and pressure Supersaturated A solution containing more solute than the saturated conditions Fig 2 on page 316 Questions 3 To make a saturated solution of KClO3 how much KClO3 is dissolved in 100 ml of water at i 20 C ii 40 C iii 60 C 4 What minimum temperature is needed to dissolve these masses of KNO3 not KClO3 in 100 ml H2O i 46 g ii 15 g iii 80 g 5 What type of solution saturated or unsaturated forms when g of KClO3 are dissolved in 100 ml of H2O at C a 43 g 85 C b 32 g 85 C c 10 g 60 C 6 100 ml H2O is saturated with KClO3 at 100 C How much KClO3 will come out of solution if the temperature is lowered to 48 C How much would precipitate under the same circumstances if 350 ml water were used 7 A saturated solution of potassium nitrate is cooled from 50 C to 10 C How many grams of KNO3 will precipitate out of 150 ml of water 3a i 7 ii 14 iii 24 25 3b i 30 C ii 3 C iii 48 C g solu per 100 g Hml 2OH 20 g te solute 100 Results of lab solubility of KClO3 4 i saturated ii unsaturated iii unsaturated 80 70 60 50 40 30 20 10 0 KNO3 Supersaturated 4 i d e t a4 ii r u t a S 4iii Unsaturated 0 20 40 60 80 Temperature oC 10 Saturation and solubility curves See Fig 2 on pg 316 Notice that there are solubility curves for many different substances Q Why do temperatures range from 0 100 C A Water is a liquid at these temperatures Solubility curves tell us how much solid will dissolve at a given temperature They also allow certain calculations Calculations using solubility curves Using fig 2 pg 316 5 100 ml H2O is saturatedwith KClO3 at 100 C How much KClO3 will come out of solution if the temperature is decreased to 48 C 57 g 18 g 39 g How much would precipitate under the same circumstances if 350 ml water were used 57 g 18 g x 3 5 137 g 6 85 g 21 g x 1 5 64 g x 1 5 96 g Solubility of gases Read page 319 of text Solubility in water Generalizations and examples