Chemical Properties of Acids and Base-I

Reactions of Acids with Metals

When an acid reacts with a metal, hydrogen gas is evolved and a corresponding salt is formed. For example, when zinc reacts with hydrochloric acid to form zinc chloride and hydrogen gas. H₂ gas extinguishes the burning splinter with a pop sound. 

• Zn(s) + 2HCl(l)  ? ZnCl₂(aq) + H₂(g)

Reactions of Bases React with Metals

A base, such as NaOH, reacts with zinc granules to form sodium zincate along with hydrogen gas. 

• 2NaOH(aq) + 2H₂O + Zn(s) ? Na₂Zn(OH)₄(s) + H₂(g)

Reaction of Acids with Metal Carbonates

An acid reacts with a metal carbonate, such as Na₂CO₃, to produce salt, water and carbon dioxide gas. 

• 2HCl(aq) + Na₂CO₃(aq) ? 2NaCl(aq) + H₂O(l) + CO₂(g) 

When the carbon dioxide gas produced during the reaction is passed through limewater, it turns milky white due to the precipitation of white calcium carbonate. 

• CO₂(g) + Ca(OH)₂(aq) ? CaCO₃(s) + H₂O(l)

However, on passing excess carbon dioxide the milky colour of the solution fades away due to the formation of water-soluble calcium bicarbonate. 

• CaCO₃(s) + H₂O(l) + CO₂(g) ? Ca(HCO₃)₂(aq)

Reaction of Bases with Metal Carbonates

However, bases generally do not react with metal carbonates to produce carbon dioxide gas. 

To perform this experiment, apparatus and chemicals are required: Test tubes in a stand, W-tube, Splinter, Bunsen burner, Hydrochloric acid, Sodium hydroxide, Zinc granules, Sodium carbonate and Limewater.

Experiment Procedure

We must follow the given procedure to understand the chemical properties of acids and bases.

1. Take a few drops of dilute HCl and NaOH solution in test tubes A and B, respectively.
2. Add a few zinc granules to both test tubes, A and B.
3. Test the gas evolved by bringing a burning splinter near the mouths of test tubes A and B.
4. Record your observations.
5. Now, take 2 W-tubes and transfer some amount of sodium carbonate into one limb and a few drops of freshly prepared limewater into the other limb of both the W-tubes. Label them A and B.
6. Transfer a few drops of HCl to the limb containing sodium carbonate and close this end of W-tube ‘A’  with the help of a dropper. Similarly, add a few drops of NaOH in W-tube ‘B’.
7. Record the change taking place in the colour of the limewater.

FAQs on Chemical Properties of Acids and Bases