1 Solutions Solutions Why does a raw egg swell or shrink Why does a raw egg swell or shrink when placed in different when placed in different solutions? solutions?
Dec 22, 2015
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SolutionsSolutions
Why does a raw egg swell or shrink when Why does a raw egg swell or shrink when placed in different solutions?placed in different solutions?
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What is a solution?What is a solution?A solution is a A solution is a
______________________________ mixture of 2 or more mixture of 2 or more substances in a substances in a single phase. single phase.
One constituent is One constituent is usually regarded as usually regarded as the the SOLVENTSOLVENT and and the others as the others as SOLUTESSOLUTES..
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Parts of a Solution• SOLUTE – the part
of a solution that is being dissolved (usually the lesser amount)
• SOLVENT – the part of a solution that dissolves the solute (usually the greater amount)
• Solute + Solvent = Solution
Solute Solvent Example
solid solid
solid liquid
gas solid
liquid liquid
gas liquid
gas gas
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Consider the solution process taking place in three distinct steps:1. separation of solvent molecules2. separation of solute molecules3. mixing of solvent and solute molecules or rate of solvation
Processes involve in Solution
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Factors that affect the rate of solvation
1. Agitating the mixture2. Increasing the surface area of the solute3. Increasing the temperature of the solvent
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What is Solubility?
Solubility refers to the maximum amount of solute that will dissolve in a given amount of solvent at a specific temperature and pressure.
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DefinitionsDefinitions
Solutions can be classified as Solutions can be classified as saturatedsaturated or or ununsaturatedsaturated..
A A saturatedsaturated solution contains solution contains the maximum quantity of the maximum quantity of solute that dissolves at that solute that dissolves at that temperature.temperature.
An An unsaturatedunsaturated solution solution contains less than the contains less than the maximum amount of solute maximum amount of solute that can dissolve at a that can dissolve at a particular temperatureparticular temperature
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DefinitionsDefinitions
SUPERSATURATED SOLUTIONSSUPERSATURATED SOLUTIONS contain more solute than is contain more solute than is possible to be dissolvedpossible to be dissolved
Supersaturated solutions are Supersaturated solutions are unstable. The supersaturation is unstable. The supersaturation is only temporary, and usually only temporary, and usually accomplished in one of two ways:accomplished in one of two ways:
1.1. Warm the solvent so that it will Warm the solvent so that it will dissolve more, then cool the dissolve more, then cool the solution solution
2. Evaporate some of the solvent carefully so that the solute does not solidify and come out of solution.
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SupersaturatedSupersaturatedSodium AcetateSodium Acetate
• One application One application of a of a supersaturated supersaturated solution is the solution is the sodium acetate sodium acetate “heat pack.”“heat pack.”
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IONIC COMPOUNDSIONIC COMPOUNDSCompounds in Aqueous SolutionCompounds in Aqueous Solution
Many reactions involve ionic Many reactions involve ionic compounds, especially reactions in compounds, especially reactions in water — water — aqueous solutions.aqueous solutions.
KMnOKMnO44 in water in water KK++(aq) + MnO(aq) + MnO44--(aq)(aq)
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How do we know ions are How do we know ions are present in aqueous present in aqueous solutions?solutions?
The solutions The solutions __________________________________________________
They are called They are called ELECTROLYTESELECTROLYTES
HCl, MgClHCl, MgCl22, and NaCl are , and NaCl are strong electrolytesstrong electrolytes. . They dissociate completely They dissociate completely (or nearly so) into ions.(or nearly so) into ions.
Aqueous Aqueous SolutionsSolutions
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Aqueous Aqueous SolutionsSolutions
Some compounds Some compounds dissolve in water but do dissolve in water but do not conduct electricity. not conduct electricity. They are called They are called nonelectrolytes.nonelectrolytes.
Examples include:Examples include:sugarsugarethanolethanolethylene glycolethylene glycol
Examples include:Examples include:sugarsugarethanolethanolethylene glycolethylene glycol
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Electrolytes in the BodyElectrolytes in the Body
Carry messages to Carry messages to
and from the brain and from the brain
as electrical signalsas electrical signals
Maintain cellular Maintain cellular
function with the function with the
correct correct
concentrations concentrations
electrolyteselectrolytes
Make your ownMake your own
50-70 g sugar50-70 g sugarOne liter of warm waterOne liter of warm waterPinch of saltPinch of salt200ml of sugar free fruit 200ml of sugar free fruit
squashsquashMix, cool and drinkMix, cool and drink
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Concentration of SoluteConcentration of SoluteConcentration of SoluteConcentration of Solute
The amount of solute in a solution The amount of solute in a solution is given by its is given by its concentrationconcentration.
Molarity (M) = moles soluteliters of solution
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1.0 L of 1.0 L of water was water was
used to used to make 1.0 L make 1.0 L of solution. of solution. Notice the Notice the water left water left
over.over.
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PROBLEM: Dissolve 5.00 g of PROBLEM: Dissolve 5.00 g of NiClNiCl22•6 H•6 H22O in enough water to O in enough water to make 250 mL of solution. make 250 mL of solution. Calculate the Molarity.Calculate the Molarity.
PROBLEM: Dissolve 5.00 g of PROBLEM: Dissolve 5.00 g of NiClNiCl22•6 H•6 H22O in enough water to O in enough water to make 250 mL of solution. make 250 mL of solution. Calculate the Molarity.Calculate the Molarity.
Step 1: Step 1: Calculate moles Calculate moles of NiClof NiCl22•6H•6H22OO
5.00 g • 1 mol
237.7 g = 0.0210 mol
0.0210 mol0.250 L
= 0.0841 M
Step 2: Step 2: Calculate MolarityCalculate Molarity
[NiClNiCl22•6 H•6 H22OO ] = 0.0841 M
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Step 1: Step 1: Change mL to L.Change mL to L.
250 mL * 1L/1000mL = 0.250 L250 mL * 1L/1000mL = 0.250 L
Step 2: Step 2: Calculate.Calculate.
Moles = (0.0500 mol/L) (0.250 L) = 0.0125 molesMoles = (0.0500 mol/L) (0.250 L) = 0.0125 moles
Step 3: Step 3: Convert moles to grams.Convert moles to grams.
(0.0125 mol)(90.00 g/mol) = (0.0125 mol)(90.00 g/mol) = 1.13 g1.13 g
USING MOLARITYUSING MOLARITYUSING MOLARITYUSING MOLARITY
moles = M•Vmoles = M•V
What mass of oxalic acid, What mass of oxalic acid, HH22CC22OO44, is, is
required to make 250. mL of a 0.0500 Mrequired to make 250. mL of a 0.0500 Msolution?solution?
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Learning Check
How many grams of NaOH are required to prepare 400. mL of 3.0 M NaOH solution?
1) 12 g
2) 48 g
3) 300 g
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Other Concentration UnitsOther Concentration Units
grams solute x 100 grams solute x 100 grams solutiongrams solution
MOLALITY, mMOLALITY, m
% by mass% by mass = =
Mass percent of soluteMass percent of solute
m of solution = mol solute
kilograms solvent
20Calculating Calculating ConcentrationsConcentrations
Dissolve 62.1 g (1.00 mol) of ethylene glycol in 250. g Dissolve 62.1 g (1.00 mol) of ethylene glycol in 250. g of Hof H22O. Calculate molality and % by mass of O. Calculate molality and % by mass of
ethylene glycol.ethylene glycol.
21Calculating Calculating ConcentrationsConcentrations
Calculate molalityCalculate molality
Calculate molalityCalculate molality
Dissolve 62.1 g (1.00 mol) of ethylene glycol in 250. g Dissolve 62.1 g (1.00 mol) of ethylene glycol in 250. g
of Hof H22O. Calculate m & % of ethylene glycol (by mass).O. Calculate m & % of ethylene glycol (by mass).
Dissolve 62.1 g (1.00 mol) of ethylene glycol in 250. g Dissolve 62.1 g (1.00 mol) of ethylene glycol in 250. g
of Hof H22O. Calculate m & % of ethylene glycol (by mass).O. Calculate m & % of ethylene glycol (by mass).
conc (molality) = 1.00 mol glycol0.250 kg H2O
4.00 molalconc (molality) = 1.00 mol glycol0.250 kg H2O
4.00 molal
%glycol = 62.1 g
62.1 g + 250. g x 100% = 19.9%%glycol =
62.1 g62.1 g + 250. g
x 100% = 19.9%
Calculate weight %Calculate weight %
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Learning Check
A solution contains 15 g Na2CO3 and 235 g of
H2O? What is the mass % of the solution?
1) 15% Na2CO3
2) 6.4% Na2CO3
3) 6.0% Na2CO3
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Parts per Million (ppm) solute= mass of solute x 106
total mass of solution
Parts per Billion (ppb) solute = mass of solute x 109
total mass of solution
Example: A 2.5 g sample of groundwater was found to contain .00054 grams of Zn2+. What is the concentration of Zn2+ in parts per million? In parts per billion?