1. Acids & Bases

2. Definition of an acid:
An acid is a substance which produces H+(aq) as the only +ve ions in water.
Examples : Name of salt
HCl hydrochloric acid monobasic chloride
H2SO sulphuric acid dibasic sulphate
HNO3 nitric acid monobasic nitrate
CH3COOH ethanoic acid monobasic ethanoate

3. Properties of dilute acids :
1. Sour taste
2. Litmus turns red , methyl orange turns red,
phenolphthalein turns colourless
3. Metals above H in e.c.s. --- give H2
Mg + 2HCl  MgCl2 + H2
4. Carbonates/hydrogencarbonates --- give CO2& H2O
K2CO3 + H2SO4  K2 SO4 + CO2 + H2O
5. Neutralize bases:
NaOH + HCl  NaCl + H2O
6. Conduct electricity (with mobile ions)

4. Properties of concentrated nitric acid :
1. As a dilute acid:
Mg + 2HNO3  Mg(NO3)2+ H2
K2CO3 + 2HNO3  2KNO3 + CO2 + H2O
NaOH + HNO3 NaNO3 + H2O
2. As an oxidizing agent:
I. Dilute nitric acid ---gives nitrogen monoxide
3Cu + 8HNO3  3Cu (NO3)2+ 2NO + 4H2O
II. Concentrated nitric acid -- gives nitrogen dioxide
Cu + 4HNO3  Cu (NO3)2+ 2NO2 + 2H2O

5. Properties of concentrated sulphuric acid :
1. As a dilute acid:
Mg + H2SO4  MgSO4 + H2
K2CO3 + H2SO4  K2SO4 + CO2 + H2O
2NaOH + H2SO4  Na2SO4 + 2H2O
2. As an oxidizing agent: gives sulphur dioxide
Cu H2SO4  CuSO4 + SO2 + 2H2O
3. As a dehydrating agent: removes elements of water
C6H12O6  6C + 6H2O
4. As a drying agent -- removes moisture

6. Definition of a base:
A base is a substance which can neutralize an acid to form a salt and water only.
Examples :
metal oxides ; metal hydroxides
CaO calcium oxide Ca(OH)2 calcium hydroxide
CuO copper(II) oxide KOH potassium hydroxide
ZnO zinc oxide NaOH sodium hydroxide
and NH3 ammonia

7. Alkalis : An alkali is a water-soluble base
They give OH– (aq) in water ; pH > 7
e.g. K+ OH– caustic potash
Na + OH– caustic soda -- to make bleach,
glass, soap
Ca 2+(OH–) 2 slaked lime -- to neutralize acid
soil
NH3 (aq) ammonia solution -- in glass
cleaners
NH H2O == NH4+ + OH–

8. Properties of solutions of alkalis :
1. Bitter taste
2. Soapy feel
3. Litmus -- blue, methyl orange -- yellow,
phenolphthalein -- pink
3. Neutralize acids -- OH- + H+  H2O
4. Give precipitates with most metal ions:
Mn+ + nOH –  M(OH)n
Cu(OH)2: pale blue Fe(OH)2: dirty green
Fe(OH)3: reddish brown
5. Give ammonia with ammonium ion

9. The pH scale 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 [H+] > [OH-]
[H+] > [OH-]
[H+] < [OH-]
acidic
alkaline
[H+] = [OH-]
neutral
It is used to show the acidity of a soln.

10. The pH of Diet Coke is 3.12
3.12

11. Measurement of pH
Methods
pH meter
7.00
pH paper
pH1 2
pH8 9

12. Experiment on measuring pH
lemon juice
acidic 3
vinegar
acidic 3
soap 10
alkaline 12
alkaline
baking soda
aspirin 5
acidic
household ammonia 12
alkaline

13. Test the pH of most common solution - pH panel