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Standard XII

Chemistry

Factors Affecting Corrosion

1 gm of an ir...

Question

1 gm of an iron are containing 50% ferrous $(F e^{2 +})$ and ferric ion $(F e^{3 +})$ and rest 50% impurities was dissolved in concentrated hydrochloric acid and the filtered solution was raised to 100 ml in flask. 50 ml of the solution were treated with M/10 $K_{2} C r_{2} O_{7}$ , which give titre value of 5 ml. Find the percentage of ferric ion in the ore

16.5

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Solution

The correct option is A 16.5
milli equivalent of $K_{2} C r_{2} O_{7} (i n 50 m l) \Rightarrow \frac{1}{10} \times 6 \times 5 = 3$
milli equivalent of $F e^{2 +}$ (in 100 ml) $=$ milli equivalent of $K_{2} C r_{2} O_{7}$ in $100 m l \Rightarrow 6$
$\frac{w}{56} \times 1000 = 6 \Rightarrow ω = 0.336$
% of $F e^{2 +} = 0.336 \times 100 = 33.6$
So, % of $F e^{3 +} = 50 - 33.6 = 16.4$

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The correct option is A 16.5milli equivalent of K2Cr2O7(in50ml)⇒110×6×5=3milli equivalent of Fe2+ (in 100 ml) = milli equivalent of K2Cr2O7 in 100ml⇒6w56×1000=6⇒ω=0.336% of Fe2+=0.336×100=33.6So, % of Fe3+=50−33.6=16.4