Balance this equation
_Al +_HCI --> _H2 +_AICIz

2Al+6HCl⇒3H₂+2AlCl₃

Equalization of chemical reaction equations can be done using variables. Steps in equalizing the reaction equation:  

•1. gives a coefficient on substances involved in the equation of reaction such as a, b, or c etc.  

•2. make an equation based on the similarity of the number of atoms where the number of atoms = coefficient × index between reactant and product  

•3. Select the coefficient of the substance with the most complex chemical formula equal to 1  

Reaction

Al+HCl⇒H₂+AlCl₃

aAl+bHCl⇒cH₂+AlCl₃

Al, left=a, right=1⇒a=1

Cl, left=b, right=3⇒b=3

H, left=b, right=2c⇒b=2c⇒3=2c⇒c=3/2

the equation becomes :

Al+3HCl⇒3/2H₂+AlCl₃ x2

2Al+6HCl⇒3H₂+2AlCl₃