Sodium carbonate(aqueous) is formed when carbon dioxide gas is passed through an
aqueous solution of sodium hydroxide. Write the balanced chemical equations of the word forms given below
Answers
Answer:1. Why is respiration considered as an exothermic process?
Solution:
Exothermic reaction is a reaction in which the energy is liberated. In the process of respiration, energy is released thus considered as an exothermic reaction
2. On what basis is a chemical equation balanced?
Solution:
A chemical equation is always balanced by comparing the number of atoms of each element on reactant side as well as product side. It is based on the Law of conservation of mass, i.e. number of atoms on the left hand side should be equal to the right hand side
3.What happens chemically when quicklime is added to water filled in a bucket?
Solution:
Quick lime is chemically calcium oxide. When it is added to water filled in a bucket, it forms calcium hydroxide (slaked lime) and reacts vigorously by releasing large amount of heat which is an exothermic reaction.
4.Why should magnesium ribbon be cleaned before burning in air?
Solution:
Magnesium ribbon is made up of pure magnesium metal and it is highly reactive with oxygen which further leads to the oxidation of magnesium when it comes in contact with air. On the surface of the magnesium ribbon it forms a layer of oxide and act as a protective layer. So it is necessary to clean the magnesium ribbon before burning in air
5. State whether the following statement is true or false:
A chemical equation can be balanced easily by altering the formula of a reactant or product.
Solution:
False
6. What is wrong with the following chemical equation?
Mg + O → MgO
Correct and balance it.
Solution:
Oxygen should be in molecular form, O2
2Mg + O2 → 2MgO
7.What does the symbol (aq) represent in a chemical equation?
Solution:
In a chemical equation (aq) always represents for aqueous solution
8.Why is photosynthesis considered an endothermic reaction?
Solution:
Endothermic reactions are those which heat is absorbed in the reaction. As we know that photosynthesis is a process that green plants and some other organisms use sunlight to synthesize food from carbon dioxide and water and turns to oxygen and glucose. Plants absorb direct energy from sun thus considered photosynthesis as endothermic reaction
9.How will you indicate the following effects in a chemical equation?
(a) A solution made in water
(b) Exothermic reaction
(c) Endothermic reaction
Solution:
(a) The solution made in water can be indicated by the symbol (aq) which shows it is aqueous
(b) An exothermic reaction can be indicated by Heat, heat energy or energy on the product side
(c) An endothermic reaction can be indicated by Heat, heat energy or energy on the reactant side
10. Translate the following statements into chemical equations and then balance the equations:
(a) Hydrogen sulphide gas burns in air to give water and sulphur dioxide.
(b) Phosphorus burns in oxygen to give phosphorus pentoxide.
(c) Carbon disulphate burns in air to give carbon dioxide and sulphur dioxide.
(d) Aluminium metal replaces iron from ferric oxide, Fe2O3, giving aluminium oxide and iron.
(e) Barium chloride reacts with zinc sulphate to give zinc chloride and barium sulphate.
Solution:
(a) 2H2S + 3O2 → 2H2O + 2SO2
(b) P4 + 5O2 → 2P2O5
(c) CS2 + 3O2 → CO2 + 2SO2
(d) 2Al + Fe2O3 → Al2O3 + 2Fe
(e) BaCl2 + ZnSO4 → ZnCl2 + BaSO4
11. Write the balanced chemical equations for the following reactions:
(a) Calcium hydroxide + Carbon dioxide → Calcium carbonate + Water
(b) Aluminium + Copper chloride → Aluminium chloride + Copper
Solution:
(a) Ca(OH)2 + CO2 → CaCO3 + H2O
(b) 2Al + 3CuCl2 → 2AlCl3 + 3Cu
Page no: 19
12.Complete and balance the following equations:
(a) NaOH + ______ → Na2SO4 + H2O
(b) Ca(OH)2 + _______ → CaCO3 + H2O
Solutions:
(a) 2NaOH + H2SO4 → Na2SO4 + 2H2O
(b) Ca(OH)2 + CO2 → CaCO3 + H2O
13.Correct and balance the following equations:
(i) Ca + H2O → CaOH + H
(ii) N + H → NH3
Solutions:
(i) Ca + 2H2O → Ca(OH)2 + H2
(ii) N2 + 3H2 →2NH3
14. Write complete balanced equations for the following reactions:
(a) Calcium (solid) + Water (liquid) →Calcium hydroxide (solution) + Hydrogen (gas)
(b) Sulphur dioxide (gas) + Oxygen (gas) → Sulphur trioxide (gas)
Solutions:
(a) Ca (s) + 2H2O (l) → Ca(OH)2 (aq) + H2 (g)
(b) 2SO2 (g) + O2 (g) → 2SO3 (g)
Explanation: