1.Chemical Reactions and Equations

Class X
Chapter 1.
Chemical Reactions and Equations
Questions Answers (NCERT Textbook)

1.1 Chemical Equations

Q.No.1. Why should a magnesium ribbon be cleaned before burning in air ?
Answer:
Magnesium ribbon is very reactive metal so it easily reacts with air and make a layer of magnesium oxide. The layer of magnesium oxide is quite stable and prevents further reaction of magnesium with air or oxygen. Therefore, magnesium ribbon is cleaned by sand paper to remove the layer of magnesium oxide before burning in air. Magnesium ribbon burns with air and gives magnesium oxide.
The word equation for the reaction would be
Magnesium + Oxygen → Magnesium Oxide.
This word equation may be represented by following chemical equation.
2Mg + O₂ → 2MgO

Q.No.2. Write the balanced equation for the following chemical reactions.
(i) Hydrogen + Chlorine → Hydrogen chloride
Answer:
The above word equation may be represented by following chemical equation
H₂ + Cl₂ → 2HCl

(ii) Barium chloride + Aluminium sulphate → Barium sulphate + Aluminium chloride
Answer:
The above word equation may be represented by
3BaCl₂ + Al₂(SO₄)₃ → 3BaSO₄ + 2AlCl₃

(iii) Sodium + Water → Sodium hydroxide + Oxygen
Answer:
The above word equation may be represented by following chemical equation.
2Na + 2H₂O → 2NaOH + H₂

Q.No.3. Write a balanced chemical equation with symbols for the following reactions.
(i) Solution of barium chloride and sodium sulphate in water react to give insoluble barium sulphate and the solution of sodium chloride.
Answer:
The above equation may be represented by following chemical equation.
BaCl₂(aq) + Na₂SO₄(aq) → BaSO₄(s) + 2NaCl(aq)

(ii) Sodium hydroxide solution (in water) reacts with hydrochloric acid solution (in water) to produce sodium chloride solution and water.
Answer:
The above equation may be represented by following chemical equation.
NaOH(aq) + HCl(aq) → NaCl(l) + H₂O(l)