acids - ionisation all acids ionise in solution to give ………ions. hcl h+ h+ h+ h+ + cl - cl -...

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+