Question 11A.19: Calculate the volume of 0.1 M NaOH solution required to neut......
Calculate the volume of 0.1 M NaOH solution required to neutralize the solution produced by dissolving 1.1 g of P_4O_6 in water.
P_4O_6 reacts with water to form phosphorous acid (H_3PO_3) as :
P _4 O _6+6 H _2 O \longrightarrow 4 H _3 PO _3 …(i)
H_3PO_3 is dibasic and it neutralizes with NaOH as :
H _3 PO _3+2 NaOH \longrightarrow Na _2 HPO _3+2 H _2 O …(ii)
Multiply eqn. (ii) by 4 and add to eqn. (i) :
\begin{matrix}P _4 O _6+&8 NaOH& \longrightarrow &4 Na _2 HPO _3&+2 H _2 O \\ &4×31+6×16 && 8(23+16+1) \\ & = 220\ g && = 320\ g \end{matrix}
Now 220 g of P_4O_6 require NaOH = 320 g
1.1 g of P_4O_6 will require NaOH for neutralization
=\frac{320}{220} \times 1.1=1.6 g
Wt. of NaOH present in 1000 mL of 0.1 M NaOH = 4 g
∴ 4g of 0.1 M NaOH is present in = 1000 mL
∴ 1.6 g of 0.1 M NaOH is present in
=\frac{1000\ \times\ 1.6}{4}=400 mL
Vol. of 0.1 M NaOH required = 400 mL.