ICSE Class 10 Chemistry Question 31 of 37

Mole Concept and Stoichiometry — Question 3

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Question

Question 3

The reaction between red lead and hydrochloric acid is given below:

Pb3O4 + 8HCl ⟶ 3PbCl2 + 4H2O + Cl2

Calculate

(a) the mass of lead chloride formed by the action of 6.85 g of red lead,

(b) the mass of the chlorine and

(c) the volume of chlorine evolved at S.T.P.

Answer

(a)

Pb3O4+8HCl3(207)+4(16)8[1+35.5]=621+64=8(36.5)=685 g=292 g3PbCl2+4H2O+Cl23[207+2(35.5)]2(35.5)=3[207+71]=71g=834 g\begin{matrix} \text{Pb}_3\text{O}_4 & + &8\text{HCl} & \longrightarrow \\ 3(207) + 4(16) & & 8[1 + 35.5] & \\ = 621 + 64 & & = 8(36.5) & \\ = 685 \text{ g} & & = 292 \text{ g} & \\ & & & \\ 3\text{PbCl}_2 & + & 4\text{H}_2\text{O} & + & \text{Cl}_2 \\ 3[207 + 2(35.5)] &&&& 2(35.5) \\ = 3[207 + 71] &&&& = 71\text{g} \\ = 834 \text{ g} \end{matrix}

685 g of Pb3O4 gives = 834 g of PbCl2

∴ 6.85 g of Pb3O4 will give

= 834685\dfrac{834}{685} x 6.85 = 8.34 g

(b) 685g of Pb3O4 gives = 71g of Cl2

∴ 6.85 g of Pb3O4 will give

= 71685\dfrac{71}{685} x 6.85 = 0.71 g of Cl2

(c) 685 g of Pb3O4 produces 22.4 L of Cl2

∴ 6.85 g of Pb3O4 will produce

22.4685\dfrac{22.4}{685} x 6.85 = 0.224 L of Cl2