Is this correct?

Question

I was asked to make this reaction acidic:
Cr2O7-2 + Zn ---> Cr+2 + Zn+2

and this is what I came up with:
Cr2O7-2 + Zn + 14H + 10e- ---> Cr+2 + Zn+2 + 7H2O + 2e-

is it right????? PLZ ITS URGENT

THANK YOU DAVID SO MUCH!!! Now I get it perfectly.

Answer 1

No, but you are in the ball park. I think I can help you. Break this into half reactions.



Cr2O7-2 + 14H+ + 8e- ---> 2Cr+2 + 7 H2O

I say 8e- because each Cr has a charge of +6 in the Cr2O7-2 because each O has a -2. 7(-2) + 2(+6) = -2.


Zn ---> Zn+2 +2e-

Once you have the half reactions you must balance them so the electrons cancel. The final equation must contain no electrons. We do this by multiplying the second half reaction by 4 and adding both equations.

4Zn ---> 4Zn+2 +8e-

Cr2O7-2 + 14H+ + 8e- ---> 2Cr+2 + 7 H2O

Final equation:

4Zn + Cr2O7-2 + 14H+ ----> 2Cr+2 + 4Zn+2 + 7 H2O


Stick with it. I appreciate that you are making an effort to learn the material. A lesser student would just throw the question out and copy the answer.

Answer 2

you had electrons on both sides
Cr2O7-2 + Zn + 14H + 10e- ---> Cr+2 + Zn+2 + 7H2O + 2e-
corrected version
Cr2O7-2 + Zn + 14H + 8e- ---> Cr+2 + Zn+2 + 7H2O
if all the charges for the ions are correct that should be corect

listen to the next guy, i dident relise that that was the while equashion

Answer 3

The reaction is not balanced, but the method of introducing H+ and H2O looks okay.

Answer 4

i think for you to balance that one,
you must ask your Chemistry professor.

always listen during lectures!