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ACIDS |
BASES |
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| Examples |
Mineral Acids:- hydrochloric acid,HCl
cleaning metals & mortar, used in swimming pools to adjust pH, found in stomach
- sulfuric acid, H2SO4
used in car batteries, used to make fertilizers (sulfate of ammonia & superphosphate), plastics, detergents, dyes, drugs, explosives
- nitric acid,HNO3
used in the manufacture of fertilizers, explosives (TNT & dynamite)
- phosphoric acid,H3PO4
used as a food acid & in anti-rust products for cars
Organic Acids:- methanoic acid (formic acid), HCOOH
found in ant stings
- ethanoic acid (acetic acid), CH3COOH
found in vinegar
- butanoic acid (butyric acid), C3H7COOH
the acid that gives rancid butter its characteristic smell
|
Alkalis (water soluble bases):- sodium hydroxide, NaOH
caustic soda
- potassium hydroxide, KOH
caustic potash
- aqueous ammonia, NH3(aq)
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| Properties |
aqueous acidic solutions:- sour taste
- turns blue litmus red
- electrical conductors
- corrode most metals
- react with carbonates & bicarbonates
- neutralise bases
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aqueous solutions of bases (soluble bases are called alkalis):- bitter taste
- change red litmus blue
- electrical conductors
- slippery feel
- neutralise acids
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Arrhenius Definitions
(1884) |
an acid ionises in water to produce hydrogen ions, H+ (protons) |
a base ionises in water to produce hydroxide ions, OH- |
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only accounts for acids that:- are aqueous solutions
- have hydrogen ions in their structure, eg, HCl
does not account for amphoteric substances (those that can act as an acid or a base)
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only accounts for bases that:- are aqueous solutions (alkalis)
- have OH- already in their structures, eg, NaOH
does not account for amphoteric substances (those that can act as an acid or a base)
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Brönsted-Lowry Definitions
(1923) |
an acid is a species that donates a proton (H+) |
a base is a species that accepts a proton (H+) |
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an amphiprotic substance can act as a proton donor and as a proton acceptor
hydrogen carbonate (bicarbonate) ion (HCO3-)is amphiprotic, it can either accept a proton to form carbonic acid (H2CO3) or it can donate a proton to form carbonate ion (CO32-) |
HB  H+ + B-
HB is acting as an acid by donating a proton, H+
B- is the conjugate base of the acid HB |
B- + H+ HB
B- is acting as a base by accepting a proton, H+
HB is the conjugate acid of the base B- |
| acid |
conjugate base |
|---|
| HCl |
Cl- |
| HNO3 |
NO3- |
| H2SO4 |
HSO4- |
| HSO4- |
SO42- |
| H2O |
OH- |
|
| base |
conjugate acid |
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| OH- |
H2O |
| NH3 |
NH4+ |
| CO32- |
HCO3- |
| HCO3- |
H2CO3 |
| H2O |
H3O+ |
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