How to balance chemical equation

Problem

Balance following chemical equation

K₂Cr₂O₇+HCl-> KCl+ CrCl₃+H₂O+ Cl₂

Solution

Step 1

Write the chemical equation as follows. 

A K₂Cr₂O₇+B HCl->C KCl+D CrCl₃+E H₂O+F Cl₂

A,B,C and D are  number of K₂Cr₂O_7,HCl_,KCl,CrCl₃ and H₂O   molecules participating in chemical reaction. 

Step 2

For a balanced equation number  of K,Cr,O,H and Cl atoms on left and right hand side should be equal

i.e. following equations are correct

K ---       2A=C

Cr ---      2A=D

O ---       7A=E

H  ---      B=2E

Cl ---      B=C+3D+2F

Step 3

Solve simultaneous equations described in step 2

B=14A

C=2A

D=2A

E=7A

F=3A

Step 4

Write balanced equation after cancelling A from left hand side and right hand side.
K₂Cr₂O₇+14HCL->2KCL+2CrCl₃+7H₂0+3ACl₂