ICSE Class 9 Chemistry Question 24 of 34

The Language of Chemistry — Question 2

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Question 2

What information does the following chemical equations convey ?

(a) Zn + H2SO4 ⟶ ZnSO4 + H2

(b) Mg + 2HCl ⟶ MgCl2 + H2

Answer

(a) Zn65+H2SO498ZnSO4161+H22\text{(a) }\underset{65}{\text{Zn}} + \underset{98}{\text{H}_2\text{SO}_4} \longrightarrow \underset{161}{\text{Zn}\text{SO}_4} + \underset{2}{\text{H}_2} \\[1em]

The above balanced equation conveys the following information:

  1. One molecule of zinc reacts with one molecule of sulphuric acid to produce one molecule of zinc Sulphate and one molecule of hydrogen.
  2. 65 g of zinc reacts with 98 g of sulphuric acid to produce 161 g of zinc Sulphate and 2 g of hydrogen.
  3. 65 g of zinc reacts with 98 g of sulphuric acid to produce 22.4 litres of hydrogen gas at S.T.P.
  4. It also proves the law of conservation of mass. According to the above equation, 163 gram of reactants are producing 163 gram of products.

(b) Mg24+2HCl73MgCl295+H22\text{(b) }\underset{24}{\text{Mg}} + \underset{73}{\text{2HCl}} \longrightarrow \underset{95}{\text{MgCl}_2} + \underset{2}{\text{H}_2} \\[1em]

The above balanced equation conveys the following information:

  1. One molecule of magnesium reacts with two molecules of hydrochloric acid to produce one molecule of magnesium chloride and one molecule of hydrogen.
  2. 24 g of magnesium reacts with 73 g of hydrochloric acid to produce 95 g of magnesium chloride and 2 g of hydrogen.
  3. 24 g of magnesium reacts with 73 g of hydrochloric acid to produce 22.4 litres of hydrogen gas at S.T.P.
  4. It also proves the law of conservation of mass. According to the above equation, 97 gram of reactants are producing 97 gram of products.