An acid is a substance, which forms H+ ions. When dissolved in water, they can conduct electricity.
Get O/A Levels & IGCSE Solved Topical Past Papers, Notes & Books
- H+ ion is proton
- Acids are called proton donors as provide H+ ions
- Turns Blue Litmus Paper Red.
- Acid reacts with Metals to produce Metal Salt + Hydrogen
Acid + MetalMetal Salt + Hydrogen
HCl + Mg MgCl2 + H2
- Acid react with bases to produce Metal Salt + Water
Acid + Metal Oxide / HydroxideMetal Salt + Water
- Acid react with Carbonates to produce Metal Salt, water and Carbondioxide
Acid + Metal CarbonateMetal Salt + Water + Salt
HCl + MgCO3 MgCl2 + H2O + CO2
Examples Of Common Acids:
Hydrochloric Acid (HCl) Sulphuric Acid ( H3PO4) and Nitric Acid
- Acids have sour taste
- They have a pH value below 7.
- Corrosive in nature. Lower the pH, more corrosive the acid becomes.
- They dissolve in H2O to form solutions that conduct electricity.
Strong and Weak Acids:
An acid that is completely ionized in solution like;
HCl H+ + Cl –
Other strong acids are Sulphuric and Nitric Acid H(NO3)2.
Partially ionizes in solution.
Some molecules remain unionized in solution like:
CH3COOH CH3COO– + H+
Other weak acids are Ethanoic, Carbonic and Sulphurous.
Distingiushing Between Weak And Strong Acid:
At the same concentration stronger acid would have the lowest pH.
The stronger acid, would be a better conductor of electricity at the same concentration.
At the same concentration and temperature, the stronger acid will react faster with solids.
All acidic properties are dependent upon the presence of H+ released by that acid. If no water is available, both organic and in organic acid will not release their H2 and finally they won’t show any acidic chemical reaction.