For the reaction, shown below, determine which statements are True and which are

Question

For the reaction, shown below, determine which statements are True and which are False.

3Fe(s) + Cr2O72-(aq) +14H+(aq) 3Fe2+(aq) + 2Cr3+(aq) + 7H2O(l)       o=1.77V

True False  The oxidation state of chromium in dichromate is +3.
True False  The oxidation state of hydrogen changes from +1 to 0.
True False  The reducing agent is Fe2+ (aq)
True False  The oxidizing agent is Fe2+ (aq)
True False  The chromium half-reaction takes place in a neutral solution.
True False  The highest oxidation state for oxygen in this reaction is 0.

Please help & explain.

Explanation / Answer

3Fe(s) + Cr2O72-(aq) +14H+(aq) 3Fe2+(aq) + 2Cr3+(aq) + 7H2O(l)       o=1.77V

True False  The oxidation state of chromium in dichromate is +3.

initially, Cr is in Cr2O7-2 present; O = -2 always so

2Cr + 7(-2) = -2

Cr =( -2 + 14)/(2) = 12/2 = +6

Therefore, this is FALSE, Cr starts with +6 oxidation state

True False  The oxidation state of hydrogen changes from +1 to 0.

H goes from H+ , i.e. +1 to H2O, which is still +1 since O = -2

H2O = 0

2H + O = 0

2H + -2 = 0

2H = +2 ; H = +1

this must be FALSE

True False  The reducing agent is Fe2+ (aq)

reducing agent --> typically oxidizes itself

Fe goes from Fe(s) , which is 0 to Fe+2, which is +2 oxidized

it lost 2 electrons, therefore this must be False, it is the reducing agent

since the reducing agent is Fe(s)

True False  The oxidizing agent is Fe2+ (aq)

False, oxidizing agents must be in the left side of the reaction

True False  The chromium half-reaction takes place in a neutral solution.

False, Cr must be in acidic medium, since H+ is the medium of eletron baance

True False  The highest oxidation state for oxygen in this reaction is 0.

False, it remains -2 in both sides

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