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Questions of balancing reactions. Any help is appreciated as I am on my final at

ID: 841317 • Letter: Q

Question

Questions of balancing reactions. Any help is appreciated as I am on my final attempt in the homework assignment, each time I have been unable to get any of them correct and if the final attempt results in a similar score, I would be unable to continue on in the course. I am looking at supplemental materials now, but any guided problem solving would be appreciated.

Answer the following questions that refer to the unbalanced reaction shown below as it occurs in acidic solution:
_______ Cr2O72-(aq) + _______ I-(aq) ? _______ Cr3++(aq) + _______ I2(s) Reference: Ref 17-3
Determine the coefficient for water in the balanced equation for the reaction.

How many electrons are transferred in the following reaction when it is balanced in acidic solution? SO32

Explanation / Answer

co-efficient of water is 7

Cr2O7^-2: the Cr oxidation state is +6
1 molecule of Cr2O7^-1 going to 2Cr^+3 gains 2 x 3 electons (6 electrons)
2 I^-1 atoms going to I2 lose 2x1 electrons (2 electrons)

You will need 3 I2 formed for each Cr2O7^-2

Cr2O7^-2 + 6I^-1 --> 2Cr^+3 + 3I2

2Cr2O7^-2 + 14H^+1 + 6I^-1 --> 2Cr^+3 + 3I2 + 7H2O

5 electrons
SO32- + H2O >> SO42- + 2H+ + 2e-)x5
MnO4- + 8H+ + 5e- >> Mn2+ + 4H2O)x2
5 SO32- + 2MnO4- + 6H+>> 5SO42- + 2Mn2+ + 3H2O


sum of the smallest whole-number coefficients is 13
*** Bi(OH)3(s) + 3H^+ + 3e^- ? Bi(s) + 3H2O
*** SnO2^2?(aq) + H2O ? SnO3^2?(aq) + 2H^+ + 2e^-
======================================...
*** 2Bi(OH)3(s) + 3SnO2^2?(aq) ? 2Bi(s) + 3SnO3^2?(aq) + 3H2O

MnO4-+ 4H+ + 3e- = MnO2 + 2 H2O )x2
I- + 3 H2O = IO3- + 6H+ + 6e-

2 MnO4- +8H+ + 6e- = 2 MnO2 + 4 H2O
I- + 3 H2O = IO3- + 6H+ + 6e-

2 MnO4- + I- + 2 H+ = 2 MnO2 + IO3- + H2O

add 2 OH- on the left and on the right
2 MnO4- + I- + H2O = 2 MnO2 + IO3- + 2 OH-

sum is 9 and co-efficeint of water is 1