Solution Chemistry
solutionof two or more substanceshomogeneous mix
solvent =solute =
substance present in major amountsubstance present in minor amount
gassolute = O2, Ar, CO2, etc.
air solvent = N2
solidsolute = C
steel solvent = Fe
liquid solvent = H2Osolute = salts, covalent compounds
H2O
O and H share electrons
separation of charge dipole
dipole moment
polar solvent
hydrogen bonds H-bondneed donor H-O
H-NH-F
acceptor ONF
but not equally
-
+
+
+
+
+
-
-
-
Aqueous solutionsNaClH2O
solvent solute
H-bondO-H+
Ion-ionNa+ Cl-
Ion-dipoleCl- H+
Na+ O-
solvation
NaCl (s) + H2O (l) Na+ (aq) + Cl- (aq)
Non-ionic solutions
C6H12O6glucosesolvent soluteH2O
H-bondO-H+
H-bondO-H+
C6H12O6 (s) + H2O (l) C6H12O6 (aq)
“Likes dissolve likes”
Non-ionic solutions
C8H18octanesolvent soluteH2O
H-bondO-H+
non-polar
C8H18 (l) + H2O (l) no reaction
Properties of aqueous solutions
ionic covalent
conduct electricity do not conduct electricityNaCl C6H12O6
electrolytes non-electrolytes
acids produce H+ in aqueous solutions
bases produce OH- in aqueous solutions
salts produce other anions and cations
produce ions
mobile, charged
Electrolytes
Rule Exceptions
1. Most acids are weak electrolytes HCl HBr HI
HNO3
H2SO4
HClO4
2. Most bases are weak electrolytesCa(OH)2 – Ba(OH)2
LiOH – CsOH
3. Most salts are strong electrolytes HgCl2
Hg(CN)2
Strong Electrolytes
dissociate completely form hydrated ions
HCl (g)
strong acids
strong basesNaOH (s) + H2O (l) Na+ (aq) + OH- (aq)
saltsMgSO4 (s) + H2O (l) Mg2+(aq) + SO4
2-(aq)
+ H2O (l) H+ (aq) + Cl- (aq)
Weak Electrolytes
do not dissociate completely
HF (g)
weak acids
+ H2O (l) + F- (aq)H+ (aq)
equilibrium all species present
NH3 (g)
weak bases
+ H2O (l) + OH- (aq)NH4+ (aq)
HgCl2 (s)
weak electrolytic salts
+ H2O (l) + 2Cl- (aq)Hg2+ (aq)
Non- Electrolytes
do not dissociate to form ions
CH3CH2OH (l)
+ H2O CH3CH2OH (aq)
Solution Compositionconcentration = amount of solute
volume of solution= mol
L= M
molarity
What is the molarity of a solution prepared by dissolving 23.4 g sodium sulfate in enough water to give 125 mL of solution?
23.4 g Na SO421 mol Na2SO4
142.0 g Na2SO4
= 0.165 mol Na2SO4
125 mL 1 L1000 mL
= .125 L M = 0.165 mol Na2SO40.125 L
= 1.32 M
[ ]
[Na2SO4] = 1.32 M
How many moles of HNO3 are present in 2.0 L of 0.200 M HNO3 solution?
0.200 mol HNO3
L
2.0 L = 0.40 mol HNO3
Solution Compositionconcentration = amount of solute
volume of solution= mol
L= M[ ]
How many grams of Na2SO4 are requiredto make 350 mL of 0.500 M Na2SO4?
0.500 mol Na2SO4
L
0.350 L1 mol Na2SO4
142.0 g = 24.9 g Na2SO4
Solution Compositionconcentration = amount of solute
volume of solution= mol
L= M[ ]
stock solution HCl = 12.0 Mmoles solute before dilution = moles solute after dilution
How would you prepare 1.5 L of a 0.10 M HCl solution?
0.10 mol HClL
1.5 L = 0.15 mol HCl
0.15 mol HCl =
moles after dilution
moles before dilution12.0 mol HCl L
= 0.0125 L
12.5 mL of 12.0 M HCl + 1.4875 L H2O = 1.50 L 0.10 M HCl
L
(x)
Solution Compositionconcentration = amount of solute
volume of solution= mol
L= M[ ]
(x)
How would you prepare 1.5 L of a 0.10 M HCl solution, usinga 12.0 M stock solution?
Mi x Vi = Mf x Vf
12.0 M HCl x Vi 0.10 M HCl x 1.5 L
Vi = 0.0125 L
then add H2O to get to Vf
=
moles of solute after dilution moles of solute before dilution =
(mol/L) (L)
=1.50 L H2O