Q23 of 44 Page 5

Identify the reducing agent in the following reactions.

(a) 4NH3 + 5O24NO+6H2O


(b) H2O +F2HF + HOF


(c) Fe2O3 + 3CO2Fe + 3CO2


(d) 2H2 + O22H2O

(a) NH3 is the reducing agent because it gets oxidised to NO by the removal of hydrogen and addition of oxygen. O2 has been reduced to H2O by the addition of hydrogen.


(b) H2O is the reducing agent because of the addition of electronegative F to get oxidised to HOF. It reduces F2 to HF by the addition of hydrogen.


(c) CO is a reducing agent. Here, CO has been oxidised to CO2 by the addition of oxygen. Fe2O3 has been reduced to Fe by the removal of oxygen.


(d) H2 is the reducing agent as it gets oxidised to H2O by the addition of oxygen. O2 has been reduced to H2O by the addition of hydrogen.


Note: A substance that donates electrons in a redox reaction is called a reducing agent. It helps in reduction by oxidising itself in a chemical reaction. A reducing agent also losses hydrogen.


More from this chapter

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21

Complete the missing components/variables given as X and Y in the following.

(a) Pb(NO3)2 (aq)+ 2Kl(aq) Pbl2 (X) + 2KNO3 (Y)


(b) Cu(s)+2AgNO3 (aq) Cu(NO3)2 (aq)+X(s)


(c) Zn(s) +H2SO4(aq)ZnSO4 (x) + H2(y)


(d) CaCO3(s) CaO(s)+CO2(g)

 22

Which among the following changes are exothermic or endothermic in nature?

(a) Decomposition of ferrous sulphate


(b) Dilution of sulphuric acid


(c) Dissolution of sodium hydroxide in water


(d) Dissolution of ammonium chloride in water

 24

Identify the oxidising agent (oxidant) in the following reactions

(a) Pb3O4 + 8HCl ⎯→ 3PbCl2 + Cl2 + 4H2O


(b) 2Mg + O2⎯→ 2MgO


(c) CuSO4 + Zn ⎯→ Cu + ZnSO4


(d) V2O5 + 5Ca ⎯→ 2V + 5CaO


(e) 3Fe + 4H2 O ⎯→ Fe3O4 + 4H2


(f) CuO + H2⎯→ Cu + H2O

 25

Write the balanced chemical equations for the following reactions

(a) Sodium carbonate on reaction with hydrochloric acid in equal molar concentrations gives sodium chloride and sodium hydrogen carbonate.


(b) Sodium hydrogen carbonate on reaction with hydrochloric acid gives sodium chloride, water and liberates carbon dioxide.


(c) Copper sulphate on treatment with potassium iodide precipitates cuprous iodide (Cu2 I2), liberates iodine gas and also forms potassium sulphate.