Answer: 4 P4 + 5 S8 => 8 P2S5
Explanation: The intial equation is
P4 + S8 => P2S5
To balance the equation we put a coefficient of 8 to P2S5 so the number of atoms for S and P are:
Reactants Products
P - 4 8 x 2 = 16
S - 8 8 x 5 = 40
To balance the reactant side we will multiply P by 4 and S by 5
Reactants Products
P - 4 x 4 = 16 2 x 8 = 16
S - 8 x 5 = 40 5 x 8 = 40
So the equation is now balanced.