Solution and Concentration in Chemistry

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SOLUTION AND CONCENTRATION

A solution is a homogeneous mixture, made up of a solute dissolved in a solvent. Ex. In a water (aqueous) solution of sodium chloride, the sodium chloride is the solute and the water is the solvent.

Solute – the component that is dissolved or is the least abundant component in the solution.Ex. Sugar, salt Solvent – the dissolving agent or the most abundant component in the solution. Ex. Water

Common Types of Solution
State of SolutionState of SoluteState of SolventExamples
GasGasGasAir
LiquidGas LiquidSoft drinks
LiquidLiquidLiquidAlcohol in water
LiquidSolidLiquidSalt in water
SolidGasSolidHydrogen in Palladium
SolidLiquidSolidMercury in silver
SolidSolidSolidSilver in gold

Kinds of Solution
1.Saturated Solution – one that contains as much of the solute as can be dissolved at the given temperature. 2.Unsaturated solution – there is less solute than can be dissolved at a given temperature 3.Supersaturated solution – unstable condition in which there is more solute in solution than can normally exist at a given time.

CONCENTRATION OF SOLUTIONS
-The concentration of solution expresses the amount of solute dissolved in a given quantity of solvent or solution. -may be expressed qualitatively and quantitatively

Dilute solution – contains a relatively small amount of dissolved solute. Concentrated solution – contains a relatively large amount of dissolved solute.
C¬1V1 = C2V2

Systems for Expressing Concentrations of Solutions
Name of SystemSymbolDefinition
MolarityMmoles of solute / liter of solution
MolalityMmoles of solute / kg of solvent
FormalityFgram-formula weight of solute /liters of solution Mole FractionN, Xmoles of solute / moles of solvent + moles of solute NormalityNequivalents of solute / liters of solution
Weight percentwt. %100 x grams of solute / grams of solvent + grams of solute Volume percentvol. %100 x liters of solute / liter of solution Parts per millionPpmmilligrams of solute / kg. of solution or milligrams / liter Parts per billionPpbmicrograms / liter

grams per volume---grams of solute / liters of solution

Concentration Units
1.Percentage Composition
a.mass or weight percent of solute – expresses the concentration of the solution as percent of solute in a given mass of solution

wt. % = wt. of solute x 100 = wt. of solute x 100 wt. of solute + solvent wt. of solution

1.a.1. What is the weight percent of sodium hydroxide in a solution that is made by dissolving 8.00 g of sodium hydroxide in 50.0 g of water?

1.a.2. What weight of potassium chloride and water are needed to make 250 g of 5.00% solution?

b.weight-volume percent – expresses the concentration as grams of solute per 100 mL of solution.

wt-vol % = wt. of solute, gram x 100
vol. of solution, mL

1.b.1. A solution was prepared by dissolving 1.30 grams silver nitrate in water and diluting to 50.0 mL. Calculate the mass-volume percent silver nitrate.

1.b.2. A 3.0% H2O2 solution is commonly used as a topical antiseptic to prevent infection. What volume of this solution will contain 10.g of H2O2?

c.volume percent (with respect to the solute). This can be used to express the concentration of a solution made by mixing two liquids.

vol. % = volume of solute x 100
volume of solution

Volume percent is used to express the concentration of alcohol in beverages. Wines generally contain 12% alcohol by volume. This translates into 12 mL of alcohol in each 100 mL of wine. The beverage industry also uses the concentration unit of proof (twice the volume percent).

Pure alcohol is 100% and therefore 200 proof. Scotch whiskey is 86 proof, or 43% alcohol.

2.Parts per million (ppm) and parts per billion (ppb)
This concentration is used for...
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