Final answer:
The C.R. formula stands for the Cation-Reduction formula, which is used to balance redox reactions by determining the change in oxidation state of the cations involved.
Step-by-step explanation:
The C.R. formula stands for the Cation-Reduction formula. It is used to balance redox reactions by determining the change in oxidation state of the cations involved. The formula is as follows:
Cr2O7^2- + 14H+ + 6e- → 2Cr3+ + 7H2O
In this example, Cr2O7^2- is reduced to Cr3+. The C.R. formula ensures that the charges and atoms on each side of the equation are balanced.