Solutions
1. SOLUTION homogeneous mixture of two or more substances solute solvent substance in a small amount substance in a large amount N2 gas phase O2 (air) Ag solid phase Au (alloys) H2O liquid phase NaCl (sea water)
iodine in ethyl alcohol (C2H5OH) EXP1 iodine in ethyl alcohol (C2H5OH) does not conduct electricity (molecular solid) I2 EXP2 table salt in water (H2O) does conduct electricity (ionic solid) Na+Cl- EXP3
AQUEOUS SOLUTION solute water (H2O) solutes solution conducts electricity solution does not conduct electricity electrolytes non-electrolytes
solution conducts electricity solution does not conduct electricity electrolytes non-electrolytes solution conducts electricity solution does not conduct electricity
non-electrolyte weak electrolyte strong electrolyte ionic compounds (NaCl, KF) NaOH HCl H2SO4 methanol sugar ethanol water CH3COOH HCOOH HF dark medium bright
SOLUTION EXP4 concentration
GAS PHASE SOLUTION Saturn solvent H2/He solute CH4, PH3
LIQUID SOLUTION Europa solvent H2O solute MgSO4
SOLID SOLUTION Triton solvent N2 solute CH4
Components of Solutions Component: a substance that is part of the solution Solvent: present in the greatest amount Solute: other than solvent (lower amount)
Mixtures that are not Solutions Colloids – appears to be a homogeneous mixture, but particles are much bigger, but not filterable. E.g. Fog, smoke, whipped cream, mayonnaise, etc. Suspension: larger particle sizes, filterable. E.g. mud, freshly squeezed orange juice.
Colloids Tyndall effect: ability of a Colloid to scatter light. The beam of light can be seen through the colloid.
Solubility and Solutions Solubility: Amount of solute that dissolves in a solvent to produce a saturated solution. (Solubility often expressed in g/100 mL.) E.g. 0.30 g of I2 dissolved in 1000 g of H2O. Saturated solution: maximum amount of solute is dissolved in solvent. Trying to dissolve more results in undissolved solute in container.
Unsaturated solution: less than max Unsaturated solution: less than max. amount of solute is dissolved in solvent. Supersaturation = more solute in solution than normally allowed; we call this a supersaturated solution.
Factors Affecting Solubility Polar liquids tend to dissolve in polar solvents due to dipole-dipole and H-bonding interactions
Factors Affecting Solubility Polar liquids tend to dissolve in polar solvents due to dipole-dipole and H-bonding interactions CH3CCH3 acetone || O CH3CH2OH ethanol Miscible: soluble in all proportions (liquids) Immiscible: do not dissolve in one another
Salt Dissolving in Water
Factors Affecting Solubility Nonpolar liquids tend to be insoluble in polar liquids; e.g. hexane (C6H14) does not dissolve in water. Increasing the nonpolar character of a substance will decrease its solubility in water.
Solubility: Temperature Dependence All solubilities are temperature dependent; Most solids are more soluble at higher temperatures. All gases are less soluble at higher temperatures.
Factors Affecting Solubility Temperature Effects
Factors Affecting Solubility Temperature Effects
Ways of Expressing Concentration Concentration: intensive property that conveys the amount of solute relative to the amount of either solvent or solution Qualitative ways: Dilute Concentrated Quantitative ways: Numeric representation Several ways
Units of Concentration Molarity Weight (mass) Percent (wt%) parts per million (ppm) and parts per billion (ppb) for small concentrations.
Molarity Convenient way to prepare solution in lab 1-L flask (1000.0 mL) Convenient way to prepare solution in lab add 0.5 mol solute dilute to mark get 0.5 M solution
Example How many grams of sulfur Hydride (H2S) must be dissolved in water to make 1L of a 0.12 M solution?
Example How many grams of sulfur Hydride (H2S) must be dissolved in 1L of water to make a 0.12 M solution? 0.12 mol x (34.09 g/1 mol) = 4.09g= 4.1 Dissolve in enough water to make 1 litre
Parts per Million (ppm) and Parts per Billion (ppb) = = 0.25 part per part
Mass percentage e.g. Solution of HCl that is 36% by mass contains 36 g of HCl for every 100 g solution