Solution Definition of Solution It is a homogeneous mixture of substances. It is a mixture that has the same properties throughout.
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Solution Definition of Solution
It is a homogeneous mixture of substances. It is a mixture that has the same properties
throughout
General Properties of Solutions Solutions are homogeneous and can vary in
their composition Solutions can generally be separated by
physical processes The solute is uniformly distributed and does
not settle out over a period of time
More Definitions Solvent
A solvent is the substance in a solution that dissolves another substance; if it is not clear which substance does the dissolving, it is the substance in the solution that is in greater amount
Solute A solute is either a substance in a solution considered to
have been dissolved in a solvent, or else a substance in a solution that is in smaller amounts
Important DefinitionsImportant DefinitionsImportant DefinitionsImportant Definitions
Solution - Solution - A homogeneous mixture consisting of one orA homogeneous mixture consisting of one ormore substances uniformly dispersed as separatemore substances uniformly dispersed as separateatoms, molecules, or ions in another substance.atoms, molecules, or ions in another substance.
Solvent - Solvent - The component of a solution that is theThe component of a solution that is the““dissolving” medium. The solvent determines thedissolving” medium. The solvent determines thephysical state of the solution (physical state of the solution (solid, liquid, or gassolid, liquid, or gas).).
Solute - Solute - The components of a solution that are “dis-The components of a solution that are “dis-solved” by the medium.solved” by the medium.
Aqueous Solution - Aqueous Solution - A solution wherein water is the A solution wherein water is the solvent.solvent.
When the solute and solvent are both in the same physicalWhen the solute and solvent are both in the same physicalstate, the one in the largest quantity is the solvent.state, the one in the largest quantity is the solvent.
Solutions homogenous mixtures mixed molecule by
molecule. Solvent - the stuff that does the dissolving. Solute -the stuff that is dissolved. Solutions can be any states Aqueous solution- a solution with water as
the solvent. Most common
Solutions Miscible- Liquids that dissolve in each
other Do not separate into layers Can be separated by distillation if boiling
points are different enough Lower boiling point evaporates fastest
More Definitions Miscible
two liquids can mix completely in one another to form a solution/homogeneous mixture.
Immiscible two liquids do not mix completely to form a
solution/homogeneous mixture.
Solubility Process How does dissolution actually take place?
Speaking from an ionic solute perspective, we saw that solvent molecules interact with the ions in the lattice structure
These attractive forces of solute/solvent are greater than the electrostatic forces in the solid
When these electrostatic forces are overcome, dissolution occurs
How Ionic solids dissolve
Called solvation. Water is a polar molecule Oxygen pulls more on the electrons Gets a partial negative charge Hydrogens get a partial positive charge Ionic compounds have + and - pieces Water breaks the + and - charged pieces apart and
surround them.
How Ionic solids dissolve
H HOH
H OH
HO
H HO
HHO
HH
O
HH
OH
H
O
HH
O
The Solution ProcessThe Solution ProcessA solution is a homogeneous mixture of solute and solvent.Solutes and solvent are components of the solution. Components may be gases, liquids or solids.The SOLVENT is the component present in largest amount.In the process of making solutions with condensed phases, intermolecular forces become rearranged.
Solution FormationThere are three energy steps in forming a solution:Separation of solute molecules
2. Separation of solvent molecules
3. Formation of solute-solvent interactions
SolutionsSolutions-If the solvent is If the solvent is water, it is called an water, it is called an aqueous solutionaqueous solution..
A dilute solution has onlyA dilute solution has onlya small amount of solute.a small amount of solute.
A concentrated solutionA concentrated solutionhas a lot of solute.has a lot of solute.
TerminologyTerminology
Types of Solutions For Liquid solutions, another distinction can
be made
Aqueous solutions are solutions that have water acting as the solvent
Nonaqueous solutions are solutions where a liquid other than water is acting as the solvent
Types of Solutions Are solutions made from only one solvent and
one solute?
By definition, there can only be one solvent However, many solutes can be dissolved in a
solvent to create a solution Air is an example of a solution with one “solvent”
(nitrogen) and many “solutes” (oxygen, helium, argon, carbon dioxide, etc.)
How Much? Solubility- The maximum amount of
substance that will dissolve at that temperature (usually g/L).
Saturated solution- Contains the maximum amount of solid dissolved.
Unsaturated solution- Can dissolve more solvent.
Supersaturated- A solution that is temporarily holding more than it can, a seed crystal will make it come out
Solubility - Solubility - The amount of The amount of solutesolute that will dissolve in a that will dissolve in agiven quantity of given quantity of solventsolvent at a given temperature. at a given temperature.
Saturated Solution - Saturated Solution - A solution that contains an amountA solution that contains an amountof of solutesolute that is equal to its solubility.that is equal to its solubility.
The dissolved solute in the solution isThe dissolved solute in the solution isin in dynamic equilibriumdynamic equilibrium with the un- with the un-dissolved solute dissolved solute (the precipitate)(the precipitate)..
Dissolved soluteDissolved solute PrecipitatePrecipitate
The rate of dissolving is equal to the rate of precipitation.The rate of dissolving is equal to the rate of precipitation.This is a This is a dynamic equilibriumdynamic equilibrium..
Unsaturated Solution - Unsaturated Solution - A solution that contains anA solution that contains anamount of amount of solutesolute that is that is lessless than its solubility. than its solubility.
All of the All of the solutesolute present is dissolved in present is dissolved inan unsaturated solution.an unsaturated solution.
Supersaturated Solution - Supersaturated Solution - A solution that contains anA solution that contains anamount of amount of solutesolute that is that is moremore than its solubility. This than its solubility. Thisis a “metastable” state (“without stability”).is a “metastable” state (“without stability”).
If disturbed in anyway, the excess soluteIf disturbed in anyway, the excess solutewill precipitate out of solution and awill precipitate out of solution and asaturated solutionsaturated solution will result. will result.
Saturated Solutions and Solubility If the solvent cannot solvate any more
molecules the solution is saturated.
The solubility of a solid in a solvent is typically given in g/100 ml.
Saturated and Unsaturated A saturated solution contains the maximum
amount of solute that can dissolve.
Undissolved solute remains.
An unsaturated solution does not contain all
the solute that could dissolve
Practice Problem: Practice Problem: If 50 mL of water at 10If 50 mL of water at 10ooC containC contain0.000 0445 g of dissolved AgCl, (a) is the solution 0.000 0445 g of dissolved AgCl, (a) is the solution unsaturated, saturated, or supersaturated? (b) is theunsaturated, saturated, or supersaturated? (b) is thesolution “dilute” or “concentrated”?solution “dilute” or “concentrated”?
The solubility of AgCl in water at 10The solubility of AgCl in water at 10ooC isC is0.000 089 g AgCl/100 mL H0.000 089 g AgCl/100 mL H22O.O.
(0.000 0445 g AgCl/50 mL H(0.000 0445 g AgCl/50 mL H22O)(100 mL HO)(100 mL H22O/100 mL HO/100 mL H22O)O)
= = 0.000 089 g AgCl/100 mL H0.000 089 g AgCl/100 mL H22OO
(a) Saturated(a) Saturated
(b) Dilute(b) Dilute
Solubility A couple of definitions:
A saturated solution is a solution obtained when you have dissolved the maximum amount of solute in a solvent at a given temperature
An unsaturated solution is any solution that contains less solute in a given volume of solvent than is contained in the saturated solution
A supersaturated solution is a solution that contains more of a solute than is contained in the saturated solution
Solubility We can also talk about these types of
solutions in terms of their equilibrium between the solid solute and the dissolved solute
Solution equilibrium is a dynamic process where the amount of solute in solution depends on how much solvent is available at a particular temperature
Solubility From an equation standpoint, we can
symbolize the solubility equilibrium of NaCl:
NaCl (s) NaCl (aq)
Where does the equilibrium lie for each of the three solutions just mentioned?
Solubility Unsaturated Solution Favors
NaCl(aq)
Saturated Solution Balanced
Supersaturated Solution Favors NaCl(s)
How would you prepare a supersaturated solution?
Solubility A beaker contains a supersaturated solution of
NaC2H3O2
What will happen if I drop a crystal of NaC2H3O2 into the solution?
TerminologyTerminologyDissolve:
solute + solvent solution.Crystallization:
solution solute + solvent.Saturation:
crystallization and dissolution are in equilibrium.
Solubility:
amount of solute required to form a saturated solution.
Supersaturated: a solution formed when more solute is dissolved than in a saturated solution.
Solubility Explanation:
The supersaturated solution is not in equilibrium The solution favors the formation of NaC2H3O2
(s) Upon the addition of a small amount of solid
NaC2H3O2, all the excess solute precipitates
Saturated Solutions and SolubilitySaturated Solutions and Solubility
Qualitative Terms: Dilute Solution – A solution in which additional solute may be
dissolved.Saturated Solution – A solution in which no more solute may
be dissolved. Supersaturated Solution – A solution in which more solute is
dissolved than in a saturated solution.Solubility - amount of solute required to form a saturated solution.
Mole Fraction, Molarity, and Molality
Solubility A couple of definitions:
A saturated solution is a solution obtained when you have dissolved the maximum amount of solute in a solvent at a given temperature
An unsaturated solution is any solution that contains less solute in a given volume of solvent than is contained in the saturated solution
A supersaturated solution is a solution that contains more of a solute than is contained in the saturated solution
Solubility When you say that a substance is “soluble” in
a particular solvent, what does that mean?
Solubility is defined as the maximum amount of a substance that dissolves in a given volume of solvent at a specified temperature
Solubility We can also talk about these types of
solutions in terms of their equilibrium between the solid solute and the dissolved solute
Solution equilibrium is a dynamic process where the amount of solute in solution depends on how much solvent is available at a particular temperature
Solubility The maximum amount of solute that can
dissolve in a specific amount of solvent usually 100 g.
g of solute
100 g water
Learning Check S1
At 40C, the solubility of KBr is 80 g/100 g H2O.
Indicate if the following solutions are
(1) saturated or (2) unsaturated
A. ___60 g KBr in 100 g of water at 40C
B. ___200 g KBr in 200 g of water at 40C
C. ___25 KBr in 50 g of water at 40C
Solution S1At 40C, the solubility of KBr is 80 g/100 g H2O.
Indicate if the following solutions are
(1) saturated or (2) unsaturated
A. 2 Less than 80 g/100 g H2O
B. 1 Same as 100 g KBr in 100 g of water
at 40C, which is greater than its solubility
C. 2 Same as 60 g KBr in 100 g of water,
which is less than its solubility
Ways of Expressing ConcentrationWays of Expressing ConcentrationAll methods involve quantifying the amount of solute per amount of solvent (or solution).• Concentration may be expressed qualitatively or quantitatively. The terms dilute and concentrated are qualitative ways to describe concentration.Quantitative expressions of concentration require specific information. The most commonly used expressions for concentration are:Mass percentage.Mole fraction.Molarity.Molality.
Ways of Expressing ConcentrationWays of Expressing Concentration
100soln of mass total
soln incomponent of mass % Mass
Ways of Expressing ConcentrationWays of Expressing Concentration
Mass Percent is one of the simplest ways to express concentration:
Parts per million (ppm) can be expressed as 1 mg of solute per Kg of solution.
Parts per billion (ppb) are 1 g of solute per kilogram of solution.
100soln of mass total
soln incomponent of masscomponent of % Mass
610soln of mass total
soln incomponent of masscomponent of ppm
Factors That Affect Solubility There are three (3) factors that affect solubility:
Nature of the solvent and solute (“Like Dissolves Like”)
Temperature Pressure
Factors That Affect Solubility “Like Dissolves Like”
A polar solvent (a molecule that has a partially positive end and a partially negative end) will dissolve ionic compounds
A nonpolar solvent will dissolve a nonpolar solute
Hydrophilic solvents (solvents that can undergo H-bonding) will dissolve hydrophilic solutes
Factors Affecting SolubilityFactors Affecting Solubility
“Like Dissolves Like”Polar molecules will dissolve in polar solvents.Non-polar molecules will dissolve in non-polar solvents.
Solute-Solvent Interactions
Solubility RulesSolubility Rules
Solute-Solvent InteractionsSolute-Solvent InteractionsPolar molecules tend to dissolve in polar solvents.Nonpolar molecules tend to dissolve in nonpolar solvents.
Like dissolves like.
Miscible liquids: mix in any proportions.Immiscible liquids: do not mix.Intermolecular forces are important: water and ethanol are miscible because the broken hydrogen bonds in both pure liquids are re-established in the mixture.
Factors Affecting SolubilityFactors Affecting Solubility
Solute-Solvent InteractionsSolute-Solvent InteractionsGeneralization: “like dissolves like”.The more polar bonds in the molecule, the better it dissolves in a polar solvent.The less polar the molecule the less it dissolves in a polar solvent and the better is dissolves in a non-polar solvent.Network solids do not dissolve because the strong intermolecular forces in the solid are not re-established in any solution.
Factors Affecting Solubility Intermolecular Forces
Hydrogen bonding Like dissolves Like
Is this correct?
H HO Cl-Na+
Factors Affecting Solubility
Intermolecular Forces Hydrogen bonding Like dissolves Like
H HO
Cl- Na+
H HO
H
HO
Factors Affecting Solubility
Intermolecular Forces Hydrogen bonding Like dissolves Like
H HO Cl- Na+
H HO
H
HO
H
HO
Solvation Separates the Ions.
Factors Affecting SolubilityFactors Affecting Solubility
Solute-Solvent InteractionsSolute-Solvent InteractionsThe number of carbon atoms in a chain affects solubility: the more C atoms the less soluble in water.
Solubilities of alcohols in water
Name Formula SolubilityMethanol CH3OH infiniteEthanol CH3CH2OH infinite1-propanol CH3CH2OH infinite1-butanol CH3CH2CH2CH2OH 80 g/L1-pentanol CH3CH2CH2CH2CH2OH 22 g/L1-hexanol CH3CH2CH2CH2CH2CH2OH 5 g/L
Making solutions
What the solute and the solvent areWhether a substance will dissolve.How much will dissolve.
A substance dissolves faster if- It is stirred or shaken. The particles are made smaller. The temperature is increased. Why?
Solubility When you say that a substance is “soluble” in
a particular solvent, what does that mean?
Solubility is defined as the maximum amount of a substance that dissolves in a given volume of solvent at a specified temperature
Why is the phrase “at a specified temperature” used here?
Factors That Affect Solubility Temperature
Normally for solid solutes, if we increase T we will increase solubility
Normally, for gaseous solutes, increasing T will decrease solubility
Temperature and Solutions
Higher temperature makes the molecules of the solvent move around faster and contact the solute harder and more often.
Speeds up dissolving. Usually increases the amount that will
dissolve.
Factors Affecting SolubilityFactors Affecting SolubilityTemperature EffectsTemperature Effects
Temperature and Solubility of Solids
Temperature Solubility (g/100 g H2O)
KCl(s) NaNO3(s)
0° 27.6 74
20°C 34.0 88
50°C 42.6 114
100°C 57.6 182
The solubility of most solids (decreases or increases ) with an increase in the temperature.
Temperature and Solubility of Solids
Temperature Solubility (g/100 g H2O)
KCl(s) NaNO3(s)
0° 27.6 74
20°C 34.0 88
50°C 42.6 114
100°C 57.6 182
The solubility of most solids increases with an increase in the temperature.
Factors Affecting SolubilityFactors Affecting SolubilityTemperature EffectsTemperature Effects
Temperature and Solubility of Gases
Temperature Solubility (g/100 g H2O)
CO2(g) O2(g)
0°C 0.34 0.0070 20°C 0.17 0.0043 50°C 0.076 0.0026
The solubility of gases (decreases or increases) with an increase in temperature.
Temperature and Solubility of Gases
Temperature Solubility (g/100 g H2O)
CO2(g) O2(g)
0°C 0.34 0.0070
20°C 0.17 0.0043
50°C 0.076 0.0026
The solubility of gases decreases with an increase in temperature.
Learning Check S2
A. Why would a bottle of carbonated drink
possibly burst (explode) when it is left out in the
hot sun ?
B. Why would fish die in water that gets too warm?
Solution S2
A. Gas in the bottle builds up as the gas becomes less soluble in water at high temperatures, which may cause the bottle to explode.
B. Because O2 gas is less soluble in warm
water, the fish may not obtain the needed
amount of O2 for their survival.
Factors That Affect Solubility Pressure
If we increase the pressure of a liquid/gas solution, we will increase the solubility of the gas into the liquid solvent
Example: soda
Factors Affecting SolubilityFactors Affecting Solubility
Solubility of a gas in a liquid is a function of the pressure of the gas.The higher the pressure, the greater the solubility.
Pressure Effects
What affects solubility?
For solids in liquids as the temperature goes up the solubility goes up.
For gases in a liquid as the temperature goes up the solubility goes down.
For gases in a liquid- as the pressure goes up the solubility goes up.
Making solutions
What the solute and the solvent areWhether a substance will dissolve.How much will dissolve.
A substance dissolves faster if- It is stirred or shaken. The particles are made smaller. The temperature is increased. Why?
Making solutions
In order to dissolve the solvent molecules must come in contact with the solute.
Stirring moves fresh solvent next to the solute.
The solvent touches the surface of the solute.
Smaller pieces increase the amount of surface of the solute.
Solubility There are number of physical phenomena that
affect the solubility (or solubility rate) of a solute
Temperature T Solubility Agitation Agitation Solubility Rate Surface Area S.A. Solubility Rate
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