SOLUTIONS Types of Solutions Solubility and Solution Process Effect of Temperature and Pressure on Solubility

Types of Solutions Gaseous Solutions Liquid Solutions Solid Solutions

In general, nonreactive gases or vapors can mix in all proportions to give a gaseous mixture. Fluids that mix with or dissolve in each other in all proportions are said to be miscible fluids. Gases are thus miscible. (If two fluids do not mix but form two layers, they are said to be immiscible.) Air, which is a mixture of oxygen, nitrogen, and smaller amounts of other gases, is an examle of a gaseous solution

Types of Solutions Liquid Solutions Most liquid solutions are obtained by dissolving a gas, liquid, or solid in some liquid. Soda water, for example, consists of a solution of carbon dioxide gas in water. Ethanol, C2H5OH, in water is an example of liquid – liquid solution. Brine is water with sodium chloride (a solid) dissolved in it.

Types of Solutions Solid Solutions Gold- silver alloy is a solid solution. Dental filling alloy is a solution of mercury (a liquid) in silver (a solid), with small amount of other metals. Solid Solutions

Classification of Solutions Diluted: A solution with a small amount of solute and large amount of solvent. Concentrated: A solution with a large amount of solute and small amount of solvent.

Classification of Solutions Saturated solution can not dissolve more solute at a given temperature. If a solution is capable of dissolving more solute, it is called unsaturated solution.

Solubility The solubilities of substances in one another vary widely. You might find a substance miscible in one solvent but nearly insoluble in another. As a general rule, “like dissolves like”. That is, similar substances disolve one another.

Solubility For example oil is miscible in gasoline. Both are mixture of hydrocarbon substances (compounds of carbon and hydrogen only). On the other hand, oil does not mix with water. Water is polar substance, whereas hydrocarbons are not.

Definition of Solubility Solubility is the concentration of solute in saturated solution. For example, the maximum amount of table salt which can dissolve in 100 g of water is 36 g at 20 oC. It means that solubility of table salt at 20 oC is 36g/100g water.

Effect of Temperature and Pressure on Solubility In general, the solubility of a substance depends on temperature. For example, the solubility of ammonium nitrate in 100 mL of water is 118 g at 0 oC and 811 g at 100 oC. Pressure may also an effect on solubility.

Temperature Effect Most gases become less soluble in water at higher temperatures. Increased temperature causes an increase in kinetic energy. The higher kinetic energy causes more motion in molecules and escape from solution.

solubility of gases usually decreases with increasing temperature Temperature Effect solubility of gases usually decreases with increasing temperature

Temperature Effect Most ionic solids become more soluble in water with rising temperature. The higher the kinetic energy of water molecules, the better the chance they have of dislodging solid molecules and thereby getting them into solution. This is so because the water molecules collide with the solid and higher collision energies lead to more effective dislodgment and thus solubility.

solubility increases with increasing temperature Temperature Effect Solubility of solids solubility increases with increasing temperature solubility decreases with increasing temperature

Pressure Effect Effect of pressure on solubility of solids and liquids is ignorable.However, solubility of gases increases with increase in pressure. When the pressure increased from P1to P2, concentration of gas molecules in solvent and therefore solubility of gas increases.

Examples: 500 g of water and 185 g of sodium chloride are mixed to make a saturated solution at 25oC. What is the solubility of NaCl at 25oC?

Answer: Solubility is defined as mass of solute in 100g of solvent. 500 g of water can dissolve 185 g of NaCl 100 g of water will dissolve ? g of NaCl ?= = 37 g of NaCl

Examples: Solubility of a solid at a certain temperature is 80 g/100 g water. How many grams of water and solid are there in 90 g of saturated solution of this solid?

Answer: 100 g of water can dissolve max. 80 g solid and forms 180 g of saturated solution. So, 180 g of solution contains 80 g of solid 90 g of solution will contain ? g of solid ?= = 40 g of solid 90 – 40 = 50 g of water

Examples: The solubility curve of the solid X as function of temperature is give aside. According to graph, How many grams of X can be dissolved in 200 g of water at 40oC ? How much more X can be dissolved in the solution prepared by adding 40 g of X and 200 g of water at 60oC ? At 60oC, saturated solution of X is prepared by 75 g of X. If the solution is cooled to 40oC, how many grams of X will precipitate? Temperature (oC) Solubility (g/100 g water) 40 60 20 50

Answer: How many grams of X can be dissolved in 200 g of water at 40oC ? According to graph at 40oC 100 g water dissolves 20 g X 200 g water ? g X ?= = 40 g of X Temperature (oC) Solubility (g/100 g water) 40 60 20 50

Answer: How much more X can be dissolved in the solution prepared by adding 40 g of X and 200 g of water at 60oC? According to graph at 60oC 100 g water dissolves 50 g X 200 g water ? g X ?= = 100 g of X Since 40 g of X is dissolved before; 100 – 40 = 60 g of X can be dissolved in the solution at 60oC. Temperature (oC) Solubility (g/100 g water) 40 60 20 50

Answer: At 60oC, saturated solution of X is prepared by 75 g of X. If the solution is cooled to 40oC, how many grams of X will precipitate? According to graph at 60oC 100 g water dissolves 50 g X ? g water 75 g X ?= = 150 g water at 40oC 100 g water dissolves 20 g X 150 g water ? g X ?= = 30 g of X Temperature (oC) Solubility (g/100 g water) 40 60 20 50 At 40oC 150 g of water can dissolve maximum 30 g of X. Therefore 75 – 30 = 45 g of X will precipitate

in this presentation… States of solution gas liquid solid Classification of solution diluted concentrated saturated unsaturated Effect of temperature and pressure on solubility