Question

Write the balanced equations for the following reactions:

Ba(OH)₂ + HBr → BaBr₂ + H₂O

Answer 1

Step 1:

Rewrite the given equation as it is 

Ba(OH)₂ + HBr → BaBr₂ + H₂O

Step 2:

write the number of atoms of each element in the unbalanced equation on both sides of the equation.

Element	Number of atoms in reactants	Number of atoms in products
Ba	1	1
Br	1	2
O	2	1
H	3	2

Step 3:

To balance the number of oxygen atoms:

Number of atoms of oxygen	In reactants	In products
To begin with	2 [in Ba(OH)2]	1 (in H2O)
To balance	2	1 × 2

To equalise the number of oxygen atoms, we use 2 as the coefficient of H₂O in the product.

Now, the partly balanced equation become as follows

Ba(OH)₂ + HBr → BaBr₂ + 2H₂O

Step 4:

Now, balance the number of hydrogen atoms. In the partly balanced equation:

Number of atoms of oxygen	In reactants	In products
To begin with	2 [in Ba(OH)2] 1 (in HBr)	4 (in 2H2O)
To balance	1 × 2 + 2	4

To equalise the number of hydrogen atoms, we use 2 as the coefficient of HBr in the reactants. Now, the equation becomes

Ba(OH)₂ + 2HBr → BaBr₂ + 2H₂O

Now, count the atoms or each element on both sides of the equation. The number of atoms on both sides are equal. Hence, the balanced equation is

Ba(OH)₂ + 2HBr → BaBr₂ + 2H₂O

Now indicate the physical states of the reactants and products.

Ba(OH)_2(aq) + 2HBr_(aq) → BaBr_2(aq) + 2H2O_(l)