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Practical no.3 Preparation Of Solutions. Solutions. Homogeneous mixture of two or more substances. The state of being dissolved. Solutions are involved in most chemical reactions,refining & purification, Industrial processing & biological processes .
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Solutions • Homogeneous mixture of two or more substances. • The state of being dissolved. • Solutions are involved in most chemical reactions,refining & purification, Industrial processing & biological processes. • Certainly there is a special place in chemistry for solutions in which water the universal solvent provides the solvent medium.Water is a versatile solvent, it dissolves something of everything and everything of something. • Solution is made up of two parts: • 1. solute • 2. solvent
SOLUTE: A solute is a substance which dissolves in the solvent and losses its physical state to form solution. • The substance or substances that are dissolved (dissolved material) • Example: salts, sugars • SOLVENT: • the substance which has the capability to disperse another substance(solute) in solution.
That substance that holds another substance in a solution. • Or the substance which dissolves the solute(dissolving medium). • Most solutions are liquid but can be solid or gases. • In solutions comprising a solid dissolved in a liquid, the liquid is the solvent and solid is solute. • If both components are liquid the one present in smaller amount is usually considered as solute. • One of the most important solutions in world,infact, is the air we breath,a combination of nitrogen,oxygen,noble gases,CO2 & water vapours.
CONCENTRATION • The proportion of solute to solvent in a given solution is expressed by the Concentration of solution. • Defined as “the amount of solute present in the given quantity of the solution” • Concentration of solutions are expressed by four ways: 1. Percent solutions 2. Molar solutions 3. Molal solutions 4. Normal solutions
PERCENT SOLUTIONS • Three ways of expressing percentage composition of a solution: • Weight by weight percent(w/w): It is weight of solute dissolved in 100g of solution. A 20% w/w solution contains 20g solute dissolved in 80g of solvent. Weight by volume percent(w/v): It is weight of solute dissolved in 100ml of solution. A 20% w/v solution contains 20g of solute dissolved in final volume of 100ml solution.
Volume by volume percent(v/v): It is volume of solute dissolved in 100ml of solution. A 20% v/v solution contains 20ml of solute dissolved in a final volume of 100ml solution.
Molar Solutions(M) • MOLARITY: It is the number of moles of the solute dissolved per litre of the solution. • Unit: moles per litre(mol/L) • Formula: Moles of solute Litres of solution A molar solution contains 1g mole of the solute dissolved in 1 L of the solution.
MOLAL SOLUTIONS • MOLALITY: It is number of moles of solute dissolved in 1000g of solvent. • A solution prepared by dissolving 180.16g of glucosein 1000g i.e 1L of water is 1 molal(1m). • Unit: mole per kg of solvent • Formula: moles of solute kg of solvent
NORMAL SOLUTIONS • NORMALITY: It is the number of gram equivalent of the solute dissolved in 1 litre of the solution. • Since equivalent weight= Molecular weight Valency in case of monovalent substance, mol wt= eq. wt M = N When valency is higher than one M = N x Valency