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Formations of Solutions. Objectives: 1.Explain the process by which solutions form. 2.Give the definition of solubility and explain how it is affected by variousfactors . KeyTerms : Solvation, hydration, solubility. Solutions.
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Formations of Solutions Objectives: • 1.Explain the process by which solutions form. • 2.Give the definition of solubility and explain how it is affected by variousfactors. KeyTerms: • Solvation, hydration, solubility
Solutions • Solutions are homogenous (looks the same) mixtures of substances in a single state. • Solutions can exist in any phase • The particles in a solution are very small - atoms, ions,molecules • Particles in a solution are evenly distributed – • one part of the solution has the same molecular make-up as another • Solutions do not separate under normal conditions • Common solution types: • alloy - solution consisting of 2 or more metals • aqueous - any solution containing water • hydrate - solution where water is the solvent
Solvation • Solvation is the term given to the interaction between solvent and solute. • If the solvent is water the reaction is called hydration - water is the most common polar solvent • solute - substance dissolved in a solution • solvent - substance that does the dissolving • soluble - substance that is capable of dissolving • Remember that “like dissolves like”… polar and ionic solutes dissolve in polar solvents and non-polar solutes in non-polar solvents • insoluble - substance that does not dissolve • miscible – soluble in any amount
Solubility • Solubility is the amount of solute that can dissolve in a solution at given conditions. • expressed in grams of solute per 100grams of solvent. • A solvent containing its maximum amount of solute is said to be saturated with solute • any amount less is unsaturated • holding more solute (past saturation point) is supersaturated • Created by cooling a saturated solution • substances that can mix in any proportions are said to be miscible • example: alcohol and water • solvent is substance with the greater amount • Substances that don't mix in any proportion are said to be immiscible • example: oil & water
Factors Affecting Solubility - Temperature • Temperature • Solubility of a gas is decreased with an increase in temperature • due to an increase in the kinetic energy of the molecules vapor pressure of the gas rises • Solubility of a solid is usually increased with an increase in temperature by increasing the KE of the solution • exception: • Exothermic rxns (reactions releasing heat) - increasing temperature decreases solubility • an increase temperature has no effect on solubility when there is no temperature change for the solution (boiling)
Factors Affecting Solubility - Pressure • Pressure • Solubility of a gas is increased with and increase in pressure (Henry's Law) • S1/P1 = S2/P2 • Solubility of a gas is directly proportional to the pressure exerted above it • Solubility of a solid is usually unaffected by pressure
Factors Affecting Solubility – Solute Size • Surface area • The greater the surface area the greater the rate of dissolving • Breaking the solute into smaller pieces increases the surface area Greater Surface Area
Factors Affecting Solubility – Stirring • Stirring - increases the rate of dissolving by bringing solvent in contact with solute