Solubility & Saturation

Solubility The solubility of a substance is the amount of that substance that will dissolve in a given amount of solvent. Quantitative – meaning a number will be applied to it grams of NaCl will completely dissolve in 100mL of water at room temperature (20°C) Therefore – the solubility of NaCl = 35.7g/100mL water at 20°C Gases can dissolve in liquid also Oxygen =.0045g/100mL water at 20°C

Factors that affect Solubility Temperature – Solubility of solids & liquids increase with increased temperature NaCl = 39.1g/100mL Water at 100°C – Solubility of gases decrease with increased temperature Oxygen =.0033g/100mL Water at 100°C – Gases typically expand greater than Liquids as temperatures increase Pressure – Mainly for Gases: The Solubility of Solids and Liquids are typically not affected by pressure

Saturated A saturated solution is one in which the dissolved solute is in equilibrium with the undissolved solute Meaning – no more solute will dissolve 35.7g of NaCl in 100mL of water at 20°C is in equilibrium and therefore – Saturated!

Concentration of Solution Defines how much solute is dissolved in a given amount of solvent – typically written as a % The parts of solute per 100 parts of solution Formula: % by mass = mass of solute/mass of solution X 100 Need to know two of three: Mass of the solute in the solution Mass of the solution Percent by Mass

Concentration of Solution How many grams of glucose and how many grams of water are in 500g in a 5.3% by mass solution of glucose solution? We know that 5.3% of the solution is glucose, so 500g of Solution X 5.3% ÷ 100 = = 26.5g of glucose 500g – 26.5g = 473.5g of water

Concentration of Solution Think of concentration in parts Part refers to ratio 7 parts Solute 9 parts Solvent 16 parts Solution Solute = 7/16 Parts = 43.75% Solvent = 9/16 Parts = 56.25%

Concentration of Solution Compare two solutions: Solution A = 15 grams sugar in 300 mL of water Solution B = 25 grams sugar in 300 mL of water Which solution is more concentrated? 15g/300mL X 100 = 5% 25g/300mL X 100 = 8.3% Solution B is more concentrated as is has a higher concentration %