Consider the equation below: Cr2 2 O2−7 7 2 − + 6Fe2+ 2 + + 14H+ + → → 2Cr3+ 3 + + 6Fe3+ 3 + + 7H2 2 O. The oxidation number of chromium changes from

Assessment: JAMB UTME - Chemistry - 2019 Subject: Chemistry

Question 1 Report

Consider the equation below:

Cr $_{2}$ O $_{7}^{2 -}$ + 6Fe $^{2 +}$ + 14H $^{+}$ $\to$ 2Cr $^{3 +}$ + 6Fe $^{3 +}$ + 7H $_{2}$ O.

The oxidation number of chromium changes from

+5 to +3

+6 to +3

-2 to +3

+7 to +3

Answer Details

Cr $_{2}$ O $_{7}^{2 -}$ + 6Fe $^{2 +}$ + 14H $^{+}$ $\to$ 2Cr $^{3 +}$ + 6Fe $^{3 +}$ + 7H $_{2}$ O
The oxidation of Cr in Cr $_{2}$ O $_{7}^{2 -}$ :
Let the oxidation of Cr = x;
2x + (-2 x 7) = -2 $⟹$ 2x - 14 = -2
2x = 12 ; x = +6
Hence, the change in oxidation of Cr = +6 to +3

Read lesson note on Oxidation And Reduction (JAMB)

Oxidation And Reduction

View Answer

Consider the equation below: Cr2 2 O2−7 7 2 − + 6Fe2+ 2 + + 14H+ + → → 2Cr3+ 3 + + 6Fe3+ 3 + + 7H2 2 O. The oxidation number of chromium changes from

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