Acids

Acids:

An acid is a substance, which forms H⁺ ions. When dissolved in water, they can conduct electricity.

E.g.

HClH⁺     +    Cl ^–

• H+ ion is proton
• Acids are called proton donors as provide H⁺   ions

General Properties:

• 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

Properties:

• 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:

Strong Acid:

An acid that is completely ionized in solution like;

HCl H⁺     +    Cl ^–

Other strong acids are Sulphuric and Nitric Acid H(NO₃)₂.

Weak Acid:

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.