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Write balanced chemical equations from the following shorthand notations. Use no

ID: 561799 • Letter: W

Question

Write balanced chemical equations from the following shorthand notations. Use no special characters for subscripts and superscripts and include the coefficient with the substance. 3Fe2+ should be written as 3Fe2+. Note that Ox1 and Red2 are the oxidizing and reducing agents, and Red1 and Ox2 are the other half of their couples.

a) Cu/Cu2+//Ag1+/Ag

b) Pb/Pb2+ // Fe2+, Fe3+/Pt

c) Pt/H1+,H2//Cu2+/Cu

d) Cr/Cr3+//H1+,H2//Pt

Please help with parts b) through d) I don't understand why my answer for part b) is wrong. My original answer to Red2 of part b) was 3Fe2+ a typo and should have been 2Fe2+, but it was marked wrong as well, so I am wondering if the platinum changes the way it is written. Please show all work! Thank you in advance!

Ox1 + Red2 Red1 + Ox2 + +

Explanation / Answer

a)

Cu is oxidised and Ag is reduced.

Cu = Cu2+
Ag+ = Ag

2Ag+ + Cu = 2Ag + Cu2+

b)

Pb is oxidised to Pb2+ and Fe3+ is reduced to Fe2+

Pb = Pb2+

Fe3+ =   Fe2+

2Fe3+ + Pb = 2Fe2+ +Pb2+

Red2 is Pb as Pb is oxidised to Pb2+ and itself acts as reducing agent.

c) H2 is oxidised to H+ and Cu2+ is reduced to Cu.

Cu2+ = Cu

H2 = H^+

Cu2+   +   H2   =   Cu + 2H^+

d)

Cr is oxidised to Cr3+ and H+ is reduced to H2

2H+ = H2

Cr = Cr3+

6H+ +2Cr = 3H2 + 2Cr3+

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