solutions. classification of matter solutions are homogeneous mixtures
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Classification of MatterSolutions are homogeneous mixtures
SoluteA solute is the dissolved substance in a solution.A solvent is the dissolving medium in a solution.SolventSalt in salt waterSugar in soda drinksCarbon dioxide in soda drinksWater in salt waterWater in soda
Types of SolutionsSolution is a homogeneius mixture of substances in the same physical state. The substances are uniformly distributed. Can contain atoms, ions, or molecules. Solid in Solid Brass (zinc with copper) A.K.A. AlloyGas in Gas Air Liquid in Liquid Alcohol in waterSolid in Liquid Salt in waterGas in Liquid Soda (CO2 in Water)A substance dissolved in water is known as an aqueous solution
Concentrated vs. DiluteConcentrated- Having more solute particles per solvent particles.
Dilute Having more solvent particles per solute particles.
Suspensions & Colloids
Suspensions and ColloidsSuspensions and colloids are NOT solutions. Suspensions: The particles are so large that they settle out of the solvent if not constantly stirred.Colloids: The particles intermediate in size between those of a suspension and those of a solution.
The Tyndall EffectColloids scatter light, making a beam visible. Solutions do not scatter light.Which glass contains a colloid?solutioncolloid
The ammeter measures the flow of electrons (current) through the circuit. If the ammeter measures a current, and the bulb glows, then the solution conducts.
If the ammeter fails to measure a current, and the bulb does not glow, the solution is non-conducting.Electrolytes vs. Nonelectrolytes
An electrolyte is: A substance whose aqueous solution conducts an electric current.A nonelectrolyte is: A substance whose aqueous solution does not conduct an electric current.Try to classify the following substances as electrolytes or nonelectrolytesDefinition of Electrolytes and Nonelectrolytes
Pure water Tap water Sugar solution Sodium chloride solution Hydrochloric acid solution Lactic acid solution Ethyl alcohol solution Pure sodium chloride Electrolytes?
ELECTROLYTES:NONELECTROLYTES: Tap water (weak) NaCl solution HCl solution Lactate solution (weak) Pure water Sugar solution Ethanol solution Pure NaCl But why do some compounds conduct electricity in solution while others do not?Answers to Electrolytes
Dissolution of sodium Chloride
How Ionic solids dissolve
Rules for Determining SolubilityTable G1. Determining Solubility: Saturated Solution Point is on the line Unsaturated Solution Point is below the line Supersaturated Solution Point is above the line
2. Interpreting the graph table GUnits on the graph are grams of solute/100g of water. If problem calls for g/200g of water or g/50g of water, double or half the grams of solute, respectively.Ex. 50g/100g of water 25g/50g of water 100g/200g of water 150g/300g of water
Practice ProblemsHow many grams of NaCl are needed to make a saturated solution at 60C?
2. How much NaNO3 is required to make a saturated solution in 100g of water at 60C? In 200g of water at 60C?
3. How much KNO3 will precipitate out of solution when a saturated solution of KNO3 is cooled from 70C to 10?
4. At 60C what type of solution is 35g of KNO3 in 100g of water? In 50g of water?
Saturation of SolutionsA solution that contains the maximum amount of solute that may be dissolved under existing conditions is saturated. A solution that contains less solute than a saturated solution under existing conditions is unsaturated. A solution that contains more dissolved solute than a saturated solution under the same conditions is supersaturated.
Saturation and Equilibrium
Solubility TrendsThe solubility of MOST solids increases with temperature. The rate at which solids dissolve increases with increasing surface area of the solid. The solubility of gases decreases with increase in temperature. The solubility of gases increases with the pressure above the solution.
ThereforeSolids tend to dissolve best when: Heated Stirred Ground into small particlesLiquids & Gases tend to dissolve best when: The solution is cold Pressure is high
Heat of SolutionThe Heat of Solution is the amount of heat energy absorbed (endothermic) or released (exothermic) when a specific amount of solute dissolves in a solvent. Table I
MolarityThe concentration of a solution measured in moles of solute per liter of solution. mol = M L
MolalityThe concentration of a solution in moles of solute per kilogram of solvent. Since the most common solvent, water, has a density of 1 kg/L, one kilogram of water is the same as one liter of water! mol = m kg
Mass Percentage, ppm, and ppbAll methods involve quantifying amount of solute per amount of solvent (or solution).Generally amounts or measures are masses, moles or liters.Qualitatively solutions are dilute or concentrated.Definitions:
Ways of Expressing Concentration
Parts per million (ppm) can be expressed as 1 mg of solute per kilogram of solution. If the density of the solution is 1g/mL, then 1 ppm = 1 mg solute per liter of solution.Parts per billion (ppb) are 1 g of solute per kilogram of solution.