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Acids and bases
Distinguishing between an acid and a base:
PH scale: higher than 7 is base
Lower than 7 is acid
Slippery feel – Basic
Litmus paper Red to bue = basic
Blue to red = Acidic
Typical properties
1
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Neutralization reactions:
Acid + Hydroxide → salt + water
Ie: HCl + NaOH → NaCl + H2O
H3PO4 + 3NaOH → Na3PO4 + 3H2O
CH3COOH + NaOH → CH3COONa + H2O
Acid + Metal Oxide → Salt + water
H2SO4 + CuO → CuSO4 + H2O
Acid + Ammonia → Salt
HCl + NH3 → NH4Cl
3
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Acid + Metal carbonate → Salt + Carbon dioxide + water
HCl + Na2CO3 → NaCl + CO2 + H2O
Metal oxides are basic
CuO(s) + H2O pH = 7 (this will create a mixture of CuO and H2O) CuO is not soluable
NaO(s) + H2O pH > 7 (this will create a solution of NaOH)

Strong and weak acids and bases
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Weak Acids
CH3COOH
Weak acids only disassociate slightly not completely
Weak bases:
NH3
C2H5NH2
Weak acids and bases are only slightly disassociated into their ions in aqueous solutions
Experiment to distinguish between strong acids and bases as well as weak acids and bases
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Ammonia behaves as a weak base in aqueous solutions
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Explain what is meant by weak and base
A base is a substance that reacts with an acid in a neutralization reaction in which a salt and
water is formed
c
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1mol/dm3 solution of ammonia To have a higher PH than a 0
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1mol ammonia has a lower PH than 0
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PH scale ranges from 0 – 14

PH < 7 is acidity
PH = 7 neutral
PH > 7 is basic
PH = -log[H+]
PH= -log
Same as concentration of hydroxide ions
PH = 1 x 7 = 7

Acid Deposition
Wet deposition – acid rain (including fog, snow and dew)
Dry deposition – acidic gases and particles
PH of rainwater = 5
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Vegetation
Many trees have been affected by the rain
2
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Buildings:
CaCO3 + H2SO4 → CaSO4 + CO2 + H2O

4
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Below ph4 lakes are dead
Presence of nitrates present in acid rain can also lead to eutrophication

Methods to improve or counteract the effects of acid rain
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Alternative energy methods: such as green energy
3
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Could be fog, snow or dew
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Acidic gases and particles occur too

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