aqueous solutions and concentration
DESCRIPTION
Aqueous Solutions and Concentration. A. Definitions. Solution - homogeneous mixture. Solute - substance being dissolved. Solvent - present in greater amount. A. Definitions. Solute - KMnO 4. Solvent - H 2 O. B. Solvation. Solvation – the process of dissolving. - PowerPoint PPT PresentationTRANSCRIPT
Aqueous Solutions and Aqueous Solutions and ConcentrationConcentration
A. DefinitionsA. DefinitionsA. DefinitionsA. Definitions
Solution - Solution - homogeneous mixturehomogeneous mixture
Solvent Solvent - present in - present in greater amountgreater amount
Solute Solute - substance - substance being dissolvedbeing dissolved
A. DefinitionsA. DefinitionsA. DefinitionsA. Definitions
Solute Solute - KMnO- KMnO44 Solvent Solvent - H- H22OO
B. SolvationB. SolvationB. SolvationB. Solvation
Solvation – Solvation – the process of dissolvingthe process of dissolving
solute particles are separated solute particles are separated and pulled into solutionand pulled into solution
solute particles are surrounded solute particles are surrounded by solvent particlesby solvent particles
B. SolvationB. SolvationB. SolvationB. Solvation
StrongElectrolyte
Non-Electrolyte
solute exists asions only
- +
salt
- +
sugar
solute exists asmolecules
only
- +
acetic acid
WeakElectrolyte
solute exists asions and
molecules DISSOCIATION IONIZATION
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B. SolvationB. SolvationB. SolvationB. Solvation
DissociationDissociationseparation of an separation of an
ionic solidionic solid into into aqueous ionsaqueous ions
NaCl(s) Na+(aq) + Cl–(aq)
B. SolvationB. SolvationB. SolvationB. Solvation
IonizationIonizationbreaking apart of breaking apart of
some some polar polar moleculesmolecules into into aqueous ionsaqueous ions
HNO3(aq) + H2O(l) H3O+(aq) + NO3–(aq)
B. SolvationB. SolvationB. SolvationB. Solvation
Molecular Molecular SolvationSolvationmoleculesmolecules
stay intactstay intact
C6H12O6(s) C6H12O6(aq)
B. SolvationB. SolvationB. SolvationB. Solvation
NONPOLAR
NONPOLAR
POLAR
POLAR
““Like Dissolves Like”Like Dissolves Like”““Like Dissolves Like”Like Dissolves Like”
B. SolvationB. SolvationB. SolvationB. Solvation
Soap/DetergentSoap/Detergentpolar “head” with long nonpolar “tail”polar “head” with long nonpolar “tail”dissolves nonpolar grease in polar waterdissolves nonpolar grease in polar water
A. ConcentrationA. ConcentrationA. ConcentrationA. Concentration
The amount of solute in a solution.The amount of solute in a solution.
Describing ConcentrationDescribing Concentration% by mass% by mass - medicated creams - medicated creams% by volume% by volume - rubbing alcohol - rubbing alcoholppm, ppbppm, ppb - water contaminants - water contaminantsmolaritymolarity - used by chemists - used by chemistsmolality molality - used by chemists- used by chemists
B. MolalityB. MolalityB. MolalityB. Molality
solvent ofkg
solute of moles(m)molality =
mass of solvent onlymass of solvent only
1 kg water = 1 L water1 kg water = 1 L water
kg 1
mol0.25 0.25m =
B. MolalityB. MolalityB. MolalityB. Molality
How many grams of NaCl are req’d to make a How many grams of NaCl are req’d to make a 1.541.54mm solution using 0.500 kg of water? solution using 0.500 kg of water?
0.500 kg water0.500 kg water 1.54 mol NaCl1.54 mol NaCl
1 kg water1 kg water
= = 45.0 g NaCl45.0 g NaCl
58.44 g NaCl58.44 g NaCl
1 mol NaCl1 mol NaCl
kg
molm=
B. MolalityB. MolalityB. MolalityB. Molality
Find the molality of a solution containing Find the molality of a solution containing 75 g of MgCl75 g of MgCl22 in 250 mL of water. in 250 mL of water.
75 g MgCl75 g MgCl22 1 mol MgCl1 mol MgCl22
95.21 g MgCl95.21 g MgCl22
= = 3.23.2mm MgCl MgCl22
0.25 kg water0.25 kg water
kg
molm =
2211 VMVM =
C. DilutionC. DilutionC. DilutionC. Dilution
Preparation of a desired solution by Preparation of a desired solution by adding water to a concentrate.adding water to a concentrate.
Moles of solute remain the same.Moles of solute remain the same.
C. DilutionC. DilutionC. DilutionC. Dilution
What volume of 15.8What volume of 15.8MM HNO HNO33 is required to make is required to make 250 mL of a 6.0250 mL of a 6.0MM solution? solution?
GIVEN:
M1 = 15.8M
V1 = ?
M2 = 6.0M
V2 = 250 mL
WORK:
M1 V1 = M2 V2
(15.8M) V1 = (6.0M)(250mL)
V1 = 95 mL of 15.8M HNO3
D. MolarityD. Molarity
Molarity is the most important unit of Molarity is the most important unit of concentration.concentration.
Molarity = Molarity = moles of solutemoles of solute
liters of solutionliters of solution
Symbol for Molarity is Symbol for Molarity is MM..
Example: A solution contains 23 g of NHExample: A solution contains 23 g of NH44Cl per 145 Cl per 145
mL solution. What is its molarity?mL solution. What is its molarity?