Acids - IonisationAll acids ionise in solution to give ………ions.
HCl H+ + Cl- (100%)
HCl (+ H2O) H3O+(aq) + Cl-(aq)
H2O + H+ H3O+
Nitric Acid: HNO3 …………………… (nitrate anion)
Sulphuric Acid: H2SO4 ……………………. (sulphate anion)
Carbonic Acid: H2CO3 ……………………. (carbonate anion)
Ethanoic acid: CH3COOH …………………….. (ethanoate anion)
Acids - IonisationAll acids ionise in solution to give H+ ions.
HCl H+ + Cl- (100%)
HCl (+ H2O) H3O+(aq) + Cl-(aq)
H2O + H+ H3O+
Nitric Acid: HNO3 H+ + NO3- (nitrate anion)
Sulphuric Acid: H2SO4 2H+ + SO42- (sulphate anion)
Carbonic Acid: H2CO3 2H+ + CO32- (carbonate anion)
Ethanoic acid: CH3COOH H+ + CH3COO-
(ethanoate anion)
BasesBases …………….acids forming a ……….+
WATER by accepting a Hydrogen ion.
NaOH(s)(+ H2O) …………. (aq)+ OH-
(aq)
NH3 + H2O …………. + OH-
NaOH + HCl …………….. + H2O
NH3 + HNO3 ……………+ NO3-
Liberate ……………. ions in water.
HF + KOH ……… + H2O
H2CO3 + 2KOH ……………+ 2H2O
Ca(OH)2(s)(+ H2O) ……………(aq)+ 2OH-(aq)
Mg(OH)2(s)(+ H2O) …………. (aq)+ 2OH-
(aq)
BasesBases neutralise acids forming a SALT + WATER
by accepting a Hydrogen ion.
NaOH(s)(+ H2O) Na+ (aq)+ OH-
(aq)
NH3 + H2O NH4+ + OH-
NaOH + HCl NaCl + H2O
NH3 + HNO3 NH4+ + NO3
-
Liberate OH- ions in water.
HF + KOH KF + H2O
H2CO3 + 2KOH K2CO3 + 2H2O
Ca(OH)2(s)(+ H2O) Ca2+ (aq)+ 2OH-
(aq)
Mg(OH)2(s)(+ H2O) Mg2+ (aq)+ 2OH-
(aq)
Bases
Soluble bases are called alkalis.
Metal Hydroxides
Metal Oxides
Metal Carbonates
Metal Hydrogen Carbonates Ammonia
NaOH CaO CaCO3 NaHCO3 NH3
Ca(OH)… Na…O Na….CO3 Ca(HCO3)... CH3NH2
Zn(OH)… Al…….. Li….CO3 Mg…………
Al………. Fe(III) .. Al….(CO3)…. Al…………
NH4……. Mn.(4+)
NH4……….. NH4…………
Bases
Soluble bases are called alkalis.
Metal Hydroxides
Metal Oxides
Metal Carbonates
Metal Hydrogen Carbonates Ammonia
NaOH CaO CaCO3 NaHCO3 NH3
Ca(OH)2 Na2O Na2CO3 Ca(HCO3)2 CH3NH2
Zn(OH)2 Al2O3 Li2CO3 Mg(HCO3)2
Al(OH)3 Fe2O3 Al2(CO3)3 Al(HCO3)3
NH4OH MnO2 (NH4)2CO3 NH4HCO3
Bases
Soluble bases are called ......................
Metal Hydroxides
Metal Oxides
Metal Carbonates
Metal Hydrogen Carbonates Ammonia
NaOH CaO CaCO3 NaHCO3 NH3
Bases
Soluble bases are called alkalis.
Metal Hydroxides
Metal Oxides
Metal Carbonates
Metal Hydrogen Carbonates Ammonia
NaOH CaO CaCO3 NaHCO3 NH3
Formula Class Test
Write the name or formula of the following ions:
1. Carbonate ion
2. Nitrite ion
3. Sulphide ion
4. SO32-
5. NH4+
6. OH-
7. O2-
Write the name or formula of each of the following compounds:
1. Sodium chloride
2. Magnesium oxide
3. Calcium hydroxide
4. Potassium sulphate
5. Cu(NO3)2
6. NH4 Cl
7. PbI
SALTS A SALT is a compound formed when a metal is ionically bonded to a
non-metal. Salts are formed in many acid-base reactions.
Acid + Metal SALT + hydrogen
Acid + Metal Oxide SALT + water
Acid + Metal hydroxide SALT + water
Acid + Metal carbonate SALT + carbon dioxide + water
Acid + Metal hydrogen carbonate SALT + carbon dioxide + water
SALT ACID BASE ACID BASE SALT
MgCl2 HCl Mg(OH)2
Fe(NO3)2 H2SO3 NaOH
MgCO3 H2CO3 CaO
Al2 (SO4 )3 H2CO3 CaCO3
(NH4)3 PO4 H2SO4 Mg.........
SALTS A SALT is a compound formed when a metal is ionically bonded to a
non-metal. Salts are formed in many acid-base reactions.
Acid + Metal SALT + hydrogen
Acid + Metal Oxide SALT + water
Acid + Metal hydroxide SALT + water
Acid + Metal carbonate SALT + carbon dioxide + water
Acid + Metal hydrogen carbonate SALT + carbon dioxide + water
SALT ACID BASE ACID BASE SALT
MgCl2 HCL Mg HCl Mg(OH)2 MgCl2
Fe(NO3)2 HNO3 Fe(OH)2 H2SO3 NaOH Na2SO3
MgCO3 H2 CO3 MgO H2CO3 CaO CaCO3
Al2 (SO4 )3 H2 SO4 Al(OH)3 H2CO3 CaCO3 CaCO3
(NH4)3 PO4 H3PO4 NH3 H2SO4 Mg MgSO4.
Cl-
Acids - ionisation2
H+
H+
H+Cl-
Cl-
Cl-
H+
H+Cl-
Cl-
20 HCl
Dilute Strong acid • all molecules
dissociated• few molecules / dm3.
Concentrated Strong Acid:
• All molecules dissociated• Many molecules per dm3
H Cl
H+Cl-
Cl-
Cl- Cl-
H+
H+
H+
H+
H+H+
H+
H+
H+
H+
H+H+H+
Cl-
Cl-Cl-
Cl-
Cl-
H Cl
(Water) (Water)
Strong - Weak Acids
5
Strong acid • all molecules dissociate
Cl-
Cl-H+
H+
Weak Acid partially ionised - hardly any ions) HF F- + H+
hydrofluoric acid fluoride ion
5
Cl-
Cl-
Cl-
H+
H+
H+
H Cl
H+
F-
H+F-
H+F- H+F-
H+F-
H+F-
Weak Acids - Ionisation
HF --> F- + H+ (partially - hardly any)hydrofluoric acid fluoride ion
Concentrated Weak acid Hardly any dissociation Lots of molecules/dm3
2H-F
F-
HF
HF
HF H+
F-
HF
HFH+
HF-20HF
Dilute Weak acid • Hardly any molecules
dissociate• few molecules / dm3.
Base Strength Strong bases ionise completely.
Weak bases ionise only ……………. (Double arrow).
NaOH(s)(+ H2O) Na+ (aq)+ OH-
(aq)
NH3 + H2O ……………… + OH-
Mg(OH)2 ……….. + 2OH-
Ca(OH)2(s)(+ H2O) ………………+ 2OH-(aq)
KOH(s)(+ H2O) K+ (aq)+ OH-
(aq)
100%
Base Strength Strong bases ionise completely.
Weak bases ionise only partially (Double arrow).
NaOH(s)(+ H2O) Na+ (aq)+ OH-
(aq)
NH3 + H2O NH4+ + OH-
Mg(OH)2 Mg2+ + 2OH-
Ca(OH)2(s)(+ H2O) Ca2+ (aq)+ 2OH-
(aq)
KOH(s)(+ H2O) K+ (aq)+ OH-
(aq)
Ionisation of waterWater molecules can ionise as follows
H2O H+ + OH-
This does not happen to any great extent so the concentration of these ions is very small.
[H+] = [OH-] ....................... mol.dm-3 (1 x 10......) at ........o C
The reaction is reversible so can be written as
H2O ...... H+ + OH-
The equilibrium constant is written as
Kw = .................
and has the value ....................mol2dm-2 at 25o C
This value ................................even if [H+] or [OH-] changes.
Ionisation of waterWater molecules can ionise as follows
H2O H+ + OH-
This does not happen to any great extent so the concentration of these ions is very small.
[H+] = [OH-] = 0.0000001 mol.dm-3 (1 x 10-7) at 25o C
The reaction is reversible so can be written as
H2O H+ + OH-
The equilibrium constant is written as
Kw = [H+] [OH-]
and has the value 1 x 10-14 mol2dm-2 at 25o C
This value does NOT change even if [H+] or [OH-] changes.
Acid strength & pH
H3O+ concentration (mol/dm3)1 0.01 0.001
............ acids ..................acids
0.0001 0.000001(1x10-4) (1x10-5)
Diluting a strong acid by a factor of ..................... changes its pH by one unit.
pH = ...........................
WEAK STRONG
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14
B A S E SA C I D S W A T E RWEAKSTRONG NEUTRAL
0.00000000000001(1x10-14)
Acid strength & pH
H3O+ concentration (mol/dm3)1 0.01 0.001
Strong acids Weak acids
0.0001 0.000001(1x10-4) (1x10-5)
Diluting a strong acid by a factor of ten changes its pH by one unit.
pH = - log10[H3O+]
WEAK STRONG[H3O+]
(mol/dm3)
Log [H3O+]
pH= -log[H3O+] 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14
B A S E SA C I D S W A T E RWEAKSTRONG NEUTRAL
1 0.1 0.01 10-3 10-4 10-5 10-6 10-7 10-8 10-9 10-10 10-11 10-12 10-13 10-14
0 -1 -2 -3 -4 -5 -6 -7 -8 -9 -10 -11 12 -13 -14
pH calculations 1Equations
pH = …………. [H+] = …………..
Example:
Calculate the pH for a specific [H+]: Given [H+] = 1.4 x 10-5 M pH =
Calculate the [H+] from pH: Given pH = 3.5
[H+] =
pH calculations 1 Equations
pH = -log10[H+] [H+] = 10-pH
Example:
Calculate the pH for a specific [H+]: Given [H+] = 1.4 x 10-5 M pH = log10[H+]
= log10(1.4 x 10-5) = 4.85
Calculate the [H+] from pH: Given pH = 3.5
[H+] = 10-pH
= 10-3.5
= 3.16 x 10-4 mol.dm-3
pH calculations 2 Strong AcidsTo work from Acid concentration.
Eg:
Calculate the pH for a 0.15 mol.dm-3 HCl solution :
Or Calculate the [H+] from pH: Given pH of a HNO3 solution is 2.5 calculate the acid concentration
pH calculations 2 Strong AcidsTo work from Acid concentration.
Eg:
Calculate the pH for a 0.15 mol.dm-3 HCl solution :
HCl a strong acid .: 100% ionised so [H+] = [HCl] = 0,15 mol.dm-3
pH = -log10[H+] = -log10(0,15) = 0.82
Or Calculate the [H+] from pH: Given pH of a HNO3 solution is 2.5 calculate the acid concentration
[HNO3] = 10-pH
= 10-2.5
= 3.16 x 10-3 mol.dm-3
pH calculations 3 Strong Polyprotic AcidsTo work from Acid concentration. Polyprotic acids
Eg:
Calculate the pH for a 0.025 mol.dm-3 H2SO4 solution :
Or Calculate the [H+] from pH: Given pH of a H3PO4 solution is 3.2 calculate the acid concentration
To work from Acid concentration. Polyprotic acids
Eg:
Calculate the pH for a 0.025 mol.dm-3 H2SO4 solution :
H2SO4 is a strong acid .: 100% ionised so
[H+] = 2x[H2SO4] = 0,05 mol.dm-3
pH = -log10[H+] = -log10(0,05) = 1.3
Or Calculate the [H+] from pH: Given pH of a H3PO4 solution is 3.2 calculate the acid concentration
[H+] = 10-pH
= 10-3.2
= 6.32 x 10-4 mol.dm-3
since H3PO4 3H+
.: [H3PO4] = 1/3 (6.32 x 10-4) = 2.1 x 10-4 mol.dm-3
pH calculations 3 Strong Polyprotic Acids
[H+] pH1. Calculate the pH of a 0.025 mol.dm-3 HNO3 solution.
2. Calculate the pH of a solution of ethanoic acid when the [H+] concentration is 1.4 x 10-4 mol.dm-3.
3. Calculate the pH of a 0,15 Molar solution of sulphuric acid.
4. Calculate the pH of a 1 M solution of H2SO3.
5. Calculate the pH of a 0.5 mol.dm-3 solution of H3PO4.
[H+] pH1. Calculate the pH of a 0.025 mol.dm-3 HNO3 solution.
2. Calculate the pH of a solution of ethanoic acid when the [H+] concentration is 1.4 x 10-4 mol.dm-3.
3. Calculate the pH of a 0,15 Molar solution of sulphuric acid.
4. Calculate the pH of a 1 M solution of H2SO3.
5. Calculate the pH of a 0.5 mol.dm-3 solution of H3PO4.
pH [H+] 1. Calculate the [H+] of a solution which has a pH of 3.
2. What concentration of HCl would give you a pH of 1.5
3. What concentration of H2SO4 would have a pH of 1?
4. What mass of HCl would need to be dissolved in 250 cm3 to give a pH of 2?
5. What would be the concentration of sulphuric acid in car batteries if the pH of the solution is 0,6?
pH [H+] 1. Calculate the [H+] of a solution which has a pH of 3.
2. What concentration of HCl would give you a pH of 1.5
3. What concentration of H2SO4 would have a pH of 1?
4. What mass of HCl would need to be dissolved in 250 cm3 to give a pH of 2?
5. What would be the concentration of sulphuric acid in car batteries if the pH of the solution is 0,6?
pH calculations Strong Base Equations
pH = -log10[H+] [H+] = 10-pH Kw = [H+] [OH-] = 1 x 10-14 mol2dm-2 at 25o C
Example:
Calculate the pH for a specific [OH-]: Given [OH-] = 1.4 x 10-5 M @ 25o C Since Kw = [H+] [OH-] = 1 x 10-14
.: [H+] = 1x10-14 / [OH-] = 1x10-14 / 1.4x10-5 = 7.1 x 10-10 M
pH = log10[H+] = log10(7.1 x 10-10) = 9.15
If the base was a strong base (say NaOH) then the base concentration would have been equal to the original OH- concentration.
I.e for STRONG BASES [BASE] = [OH-]
In the Lowry-Brønsted model, an acid is a ............. donor and a base is a proton acceptor.
acid conj. ........................
Why do we say the A- is a base?
HA H+ + A-
In the Lowry-Brønsted model, an acid is a proton donor and a base is a proton accep-tor.
acid conj. baseproton
Why do we say the A- is a base? It ACCEPTS a proton
HA H+ + A-
The HA and A- is called an acid-base pair.Examples:
The HA and A- is called an acid-base pair.Examples:
Take note that a strong acid has a weakconjugate base and a strong base has a weak conjugate acid and vice versa.
HCl H+ + Cl-
...............acid ...........conj. base
H2O H+ + OH-
............... acid ................conj. base
Take note that a strong acid has a weakconjugate base and a strong base has a weak conjugate acid and vice versa.
HCl H+ + Cl-
strong acid weak conj. base
H2O H+ + OH-
weak acid strong conj. base
Protolytic Reactions
Identify the acid base pairs in the following: HNO3 + KOH KNO3 + H2O
H2CO3 + MgO MgCO3 + CO2 + H2O
Protolytic Reactions
HNO3 + KOH KNO3 + H2O
a1 b2 b1 a2
H2CO3 + MgO MgCO3 + CO2 + H2O
a1 b2 b1 a2
H2PO4 - HPO42- + H+
AMPHOLYTES
H2PO4 - + H+ H3PO4
H2PO4 - HPO42- + H+
AMPHOLYTES
H2PO4 - + H+ H3PO4
HCO3 - + H+ H2CO3
HCO3 - CO32-
+ H+
H2O H+ + OH-
H2O + H+ H3O+