JEE MAIN - Chemistry (2021 - 17th March Morning Shift - No. 16)
15 mL of aqueous solution of Fe2+ in acidic medium completely reacted with 20 mL of 0.03 M aqueous Cr2O$$_7^{2 - }$$. The molarity of the Fe2+ solution is __________ $$\times$$ 10-2 M. (Round off to the Nearest Integer).
Answer
24
Explanation
$$C{r_2}{O_7}^{2 - } + F{e^{2 + }}\mathrel{\mathop{\kern0pt\longrightarrow}
\limits_{}} C{r^{3 + }} + F{e^{3 + }}$$
Valance Factor of $$C{r_2}{O_7}^{2 - }$$ = 6
Valance Factor of $$F{e^{2 + }}$$ = 1
mili eq. of $$C{r_2}{O_7}^{2 - }$$ = mili eq. of Fe2+
6(0.03 $$\times$$ 20) = 1(M $$\times$$ 15)
M = 6(0.03)4/3
M = 0.24 M
M = 24 $$\times$$ 10$$-$$2 M
Valance Factor of $$C{r_2}{O_7}^{2 - }$$ = 6
Valance Factor of $$F{e^{2 + }}$$ = 1
mili eq. of $$C{r_2}{O_7}^{2 - }$$ = mili eq. of Fe2+
6(0.03 $$\times$$ 20) = 1(M $$\times$$ 15)
M = 6(0.03)4/3
M = 0.24 M
M = 24 $$\times$$ 10$$-$$2 M
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