Question

Fill in the coefficients that will balance the following reaction: a0PbI4 + a1CrCl3 → a2PbCl4 + a3CrI3

Answer 1

a0 = 3, a1 = 4, a2 = 3, a3 = 4.

Answer 2

PbI₄ + CrCl₃ --> PbCl₄ + CrI₃

There is 1 Pb and Cr atom on both sides.
There are 3 Cl atoms on the left side and 4 on the right side.
There are 4 I atoms on the left side and 3 on the right side.

PbI₄ + 4CrCl₃ --> 3PbCl₄ + CrI₃
Cl atoms are now balanced

3PbI₄ + 4CrCl₃ --> 3PbCl₄ + 4CrI₃
All of the atoms are now balanced.

3PbI₄ + 4CrCl₃ --> 3PbCl₄ + 4CrI₃