Write the balanced equation for the following chemical reactions:

Sodium + Water → Sodium hydroxide + Hydrogen

  1. 2Na(s) + 2H 2 O(l) → 2NaOH(aq) + H 2 (g)

 

  1. Na(s) + H 2 O(l) → NaOH(aq) + H 2 (g)

 

  1. 2Na(s) + 2H 2 O(l) → NaOH(aq) + H 2 (g)

 

  1. Na(s) + H 2 O(l) → 2NaOH(aq) + H 2 (g)

 

Answer

  1. 2Na(s) + 2H 2 O(l) → 2NaOH(aq) + H 2 (g)

 

Explanation - In a balanced chemical equation, the number of atoms of each element is balanced on the left and right side of the equation.

 

  • Na(s) + H 2 O(l) → NaOH(aq) + H 2 (g) [ Unbalanced equation ]

 

 

Reactants

Products

Na

1

1

O

1

1

H

2

3

 

  • Na(s) + H 2 O(l) → 2 NaOH(aq) + H 2 (g)

 

 

Reactants

Products

Na

1

2

O

1

2

H

2

4

 

  • 2 Na(s) + 2 H 2 O(l) → 2NaOH(aq) + H 2 (g)

 

 

Reactants

Products

Na

2

2

O

2

2

H

4

4

 

  • 2Na(s) + 2H 2 O(l) → 2NaOH(aq) + H 2 (g) [ Balanced Equation ]



Balance the equation P 4 O 10 + H 2 O → H 3 PO 4

 

Answer

  • P 4 O 10 + H 2 O → H 3 PO 4  [ Unbalanced Equation ]

 

 

Reactants

Products

P

4

1

O

11

4

H

2

3

 

  • P 4 O 10 + H 2 O → 4 H 3 PO

 

 

Reactants

Products

P

4

4

O

11

16

H

2

12

  • P 4 O 10 + 6 H 2 O → 4H 3 PO

 

 

Reactants

Products

P

4

4

O

16

16

H

12

12

 

  • P 4 O 10 + 6H 2 O → 4H 3 PO 4   [ Balanced Equation ]




Balance the equation CO 2 + H 2 O → C 6 H 12 O 6 + O 2

 

Answer

  • CO 2 + H 2 O → C 6 H 12 O 6 + O 2   [ Unbalanced Equation ]

 

 

Reactants

Products

C

1

6

O

3

8

H

2

12

 

  • 6 CO 2 + H 2 O → C 6 H 12 O 6 + O 2  

 

 

Reactants

Products

C

6

6

O

13

8

H

2

12

 

  • 6CO 2 + 6 H 2 O → C 6 H 12 O 6 + O 2  

 

 

Reactants

Products

C

6

6

O

18

8

H

12

12

 

  • 6CO 2 + 6H 2 O → C 6 H 12 O 6 + 6 O 2  

 

 

Reactants

Products

C

6

6

O

18

18

H

12

12

 

  • 6CO 2 + 6H 2 O → C 6 H 12 O 6 + 6O 2   [ Balanced Equation ]




Balance the equation SiCl 4 + H 2 O → H 4 SiO 4 + HCl

 

Answer

  • SiCl 4 + H 2 O → H 4 SiO 4 + HCl [ Unbalanced Equation ]

 

 

Reactants

Products

Si

1

1

Cl

4

1

O

1

4

H

2

5

 

  • SiCl 4 + H 2 O → H 4 SiO 4 + 4 HCl 

 

 

Reactants

Products

Si

1

1

Cl

4

4

O

1

4

H

2

8

 

  • SiCl 4 + 4 H 2 O → H 4 SiO 4 + 4HCl

 

 

Reactants

Products

Si

1

1

Cl

4

4

O

4

4

H

8

8

 

  • SiCl 4 + 4H 2 O → H 4 SiO 4 + 4HCl  [ Balanced Equation ]



Balance the equation Fe + H 2 O → Fe 3 O 4 + H 2

 

Answer

  • Fe + H 2 O → Fe 3 O 4 + H 2   [ Unbalanced Equation ]

 

 

Reactants

Products

Fe

1

3

H

2

2

O

1

4

 

  • 3 Fe + H 2 O → Fe 3 O 4 + H 2

 

 

Reactants

Products

Fe

3

3

H

2

2

O

1

4

 

  • 3Fe + 4 H 2 O → Fe 3 O 4 + H 2

 

 

Reactants

Products

Fe

3

3

H

8

2

O

4

4

 

  • 3Fe + 4H 2 O → Fe 3 O 4 + 4 H 2

 

 

Reactants

Products

Fe

3

3

H

8

8

O

4

4

 

  • 3Fe + 4H 2 O → Fe 3 O 4 + 4H 2  [ Balanced Equation ]




Balance the equation MnO 2 + HCl →  MnCl 2 + Cl 2 + H 2 O

 

Answer

  • MnO 2 + HCl →  MnCl 2 + Cl 2 + H 2 O  [ Unbalanced Equation ]

 

 

Reactants

Products

Mn

1

1

Cl

1

4

O

2

1

H

1

2

 

  • MnO 2 + 4 HCl →  MnCl 2 + Cl 2 + H 2 O

 

 

Reactants

Products

Mn

1

1

Cl

4

4

O

2

1

H

4

2

 

  • MnO 2 + 4HCl →  MnCl 2 + Cl 2 + 2 H 2 O

 

 

Reactants

Products

Mn

1

1

Cl

4

4

O

2

2

H

4

4

 

  • MnO 2 + 4HCl →  MnCl 2 + Cl 2 + 2H 2 [ Balanced Equation ]




Balance the equation HNO 3 + Ca(OH) 2 → Ca(NO 3 ) 2 + H 2 O

 

Answer

  •  HNO 3 + Ca(OH) 2 → Ca(NO 3 ) 2 + H 2 [ Unbalanced Equation ]

 

 

Reactants

Products

N

1

2

Ca

1

1

O

5

7

H

3

2

 

  •   2 HNO 3 + Ca(OH) 2 → Ca(NO 3 ) 2 + H 2 O

 

 

Reactants

Products

N

2

2

Ca

1

1

O

8

7

H

4

2

 

  •  2HNO 3 + Ca(OH) 2 → Ca(NO 3 ) 2 + 2 H 2 O

 

 

Reactants

Products

N

2

2

Ca

1

1

O

8

8

H

4

4

 

  •  2HNO 3 + Ca(OH) 2 → Ca(NO 3 ) 2 + 2H 2 O  [ Balanced Equation ]





Balance the equation Al + HCl → AlCl 3 + H 2

 

Answer

  • Al + HCl → AlCl 3 + H [ Unbalanced Equation ]

 

 

Reactants

Products

Al

1

1

Cl

1

3

H

1

2

 

  • Al + 3 HCl → AlCl 3 + H 2  

 

 

Reactants

Products

Al

1

1

Cl

3

3

H

3

2

 

  • Al + (3x2) HCl → AlCl 3 + 3 H

Al +    6   HCl → AlCl 3 + 3 H

 

 

Reactants

Products

Al

1

1

Cl

6

3

H

6

6

 

  • Al + 6HCl → 2 AlCl 3 + 3H 2  

 

 

Reactants

Products

Al

1

2

Cl

6

6

H

6

6

 

  • 2 Al + 6HCl → 2AlCl 3 + 3H

 

 

Reactants

Products

Al

2

2

Cl

6

6

H

6

6

 

  • 2Al + 6HCl → 2AlCl 3 + 3H 2  [ Balanced Equation ]




Balance the equation Na 2 CO 3 + HCl → NaCl + H 2 O + CO 2

 

Answer

  • Na 2 CO 3 + HCl → NaCl + H 2 O + CO 2   [ Unbalanced Equation ]

 

 

Reactants

Products

Na

2

1

C

1

1

Cl

1

1

O

3

3

H

1

2

 

  • Na 2 CO 3 + HCl → 2 NaCl + H 2 O + CO 2

 

 

Reactants

Products

Na

2

2

C

1

1

Cl

1

2

O

3

3

H

1

2

 

  • Na 2 CO 3 + 2 HCl → 2NaCl + H 2 O + CO 2

 

 

Reactants

Products

Na

2

2

C

1

1

Cl

2

2

O

3

3

H

2

2

 

  • Na 2 CO 3 + 2HCl → 2NaCl + H 2 O + CO 2  [ Balanced Equation ]




Balance the equation C 7 H 6 O 2 + O 2 → CO 2 + H 2 O

 

Answer

  • C 7 H 6 O 2 + O 2 → CO 2 + H 2 O  [ Unbalanced Equation ]

 

 

Reactants

Products

C

7

1

H

6

2

O

4

3

 

  • C 7 H 6 O 2 + O 2 7 CO 2 + H 2 O

 

 

Reactants

Products

C

7

7

H

6

2

O

4

15

 

  • C 7 H 6 O 2 + O 2 → 7CO 2 + 3 H 2 O

 

 

Reactants

Products

C

7

7

H

6

6

O

4

17

 

Now, Oxygen needs to be balanced and Oxygen is present in 2 molecules; C 7 H 6 O 2 and O 2 .

For convenience is solving the equation for Oxygen, let us multiply the whole equation by 2 so that the coefficients are even numbers.

 

  • 2 C 7 H 6 O 2 + 2 O 2 14 CO 2 + 6 H 2 O

 

 

Reactants

Products

C

14

14

H

12

12

O

8

34

 

  • 2C 7 H 6 O 2 + 15 O 2 → 14CO 2 + 6H 2 O

 

 

Reactants

Products

C

14

14

H

12

12

O

34

34

 

  • 2C 7 H 6 O 2 + 15O 2 → 14CO 2 + 6H 2 O  [ Balanced Equation ]




Balance the equation Fe 2 (SO 4 ) 3 + KOH → K 2 SO 4 + Fe(OH) 3

 

Answer

  • Fe 2 (SO 4 ) 3 + KOH → K 2 SO 4 + Fe(OH) 3

 

 

Reactants

Products

Fe

2

1

S

3

1

K

1

2

O

13

7

H

1

3

 

  • Fe 2 (SO 4 ) 3 + KOH → K 2 SO 4 + 2 Fe(OH) 3

 

 

Reactants

Products

Fe

2

2

S

3

1

K

1

2

O

13

10

H

1

6

 

  • Fe 2 (SO 4 ) 3 + KOH → 3 K 2 SO 4 + 2Fe(OH) 3

 

 

Reactants

Products

Fe

2

2

S

3

3

K

1

6

O

13

18

H

1

6

 

  • Fe 2 (SO 4 ) 3 + 6 KOH → 3K 2 SO 4 + 2Fe(OH) 3

 

 

Reactants

Products

Fe

2

2

S

3

3

K

6

6

O

18

18

H

6

6

 

  • Fe 2 (SO 4 ) 3 + 6KOH → 3K 2 SO 4 + 2Fe(OH) [ Balanced Equation ]



Balance the equation Ca 3 (PO 4 ) 2 + SiO 2 → P 4 O 10 + CaSiO 3

 

Answer

Ca (PO 4 ) 2 + SiO 2 → P 4 O 10 + CaSiO 3

 

 

Reactants

Products

Ca

3

1

P

1

4

Si

1

1

O

10

13

 

  • Ca 3 (PO 4 ) 2 + SiO 2 → P 4 O 10 + 3 CaSiO 3

 

 

Reactants

Products

Ca

3

3

P

2

4

Si

1

3

O

10

19

 

  • 2 Ca 3 (PO 4 ) 2 + SiO 2 → P 4 O 10 + 3CaSiO 3

 

 

Reactants

Products

Ca

6

3

P

4

4

Si

1

3

O

16

19

 

Now Ca has to be balanced again, so;

  • 2Ca 3 (PO 4 ) 2 + SiO 2 → P 4 O 10 + 6 CaSiO 3

 

 

Reactants

Products

Ca

6

6

P

4

4

Si

1

6

O

16

28

 

  • 2Ca 3 (PO 4 ) 2 + 6 SiO 2 → P 4 O 10 + 6CaSiO 3

 

 

Reactants

Products

Ca

6

6

P

4

4

Si

6

6

O

28

28

 

  • 2Ca 3 (PO 4 ) 2 + 6SiO 2 → P 4 O 10 + 6CaSiO 3   [ Balanced Equation ]

 

Balance the equation KClO 3 → KClO 4 + KCl

 

Answer

  • KClO 3 → KClO 4 + KCl

 

 

Reactants

Products

K

1

2

Cl

1

2

O

3

4

 

This question requires a slightly different approach.

Here we can see that all atoms are balanced except Oxygen. So we can start with Oxygen by cross multiplying the terms with Oxygen

 

  • 4 KClO 3 3 KClO 4 + KCl

 

 

Reactants

Products

K

4

4

Cl

4

4

O

12

12

 

Now, since the other elements are also balanced, the equation is balanced. 

 

  • 4KClO 3 → 3KClO 4 + KCl  [ Balanced Equation ]



Balance the equation Al 2 (SO 4 ) 3 + Ca(OH) 2 → Al(OH) 3 + CaSO 4



Answer

  • Al 2 (SO 4 ) 3 + Ca(OH) 2 → Al(OH) 3 + CaSO 4

 

 

Reactants

Products

Al

2

1

S

3

1

Ca

1

1

O

14

7

H

2

3

 

  • Al 2 (SO 4 ) 3 + Ca(OH) 2 2 Al(OH) 3 + CaSO 4

 

 

Reactants

Products

Al

2

2

S

3

1

Ca

1

1

O

14

10

H

2

6

 

  • Al 2 (SO 4 ) 3 + Ca(OH) 2 → 2Al(OH) 3 + 3 CaSO 4

 

 

Reactants

Products

Al

2

2

S

3

3

Ca

1

3

O

14

18

H

2

6

 

  • Al 2 (SO 4 ) 3 + 3 Ca(OH) 2 → 2Al(OH) 3 + 3CaSO 4



 

Reactants

Products

Al

2

2

S

3

3

Ca

3

3

O

18

18

H

6

6

 

  • Al 2 (SO 4 ) 3 + 3Ca(OH) 2 → 2Al(OH) 3 + 3CaSO   [ Balanced Equation ]




Balance the equation H 2 SO 4 + HI → H 2 S + I 2 + H 2 O



Answer

  • H 2 SO 4 + HI → H 2 S + I 2 + H 2 O  [ Unbalanced Equation ]

 

 

Reactants

Products

S

1

1

I

1

2

O

4

1

H

3

4

 

  • H 2 SO 4 + 2 HI → H 2 S + I 2 + H 2 O

 

 

Reactants

Products

S

1

1

I

2

2

O

4

1

H

4

4

  • H 2 SO 4 + 2HI → H 2 S + I 2 + 4 H 2 O

 

 

Reactants

Products

S

1

1

I

2

2

O

4

4

H

4

10

 

H needs to be balanced further,

  • H 2 SO 4 + 8 HI → H 2 S + 4 I 2 + 4H 2 O

 

 

Reactants

Products

S

1

1

I

8

8

O

4

4

H

10

10

 

  • H 2 SO 4 + 8HI → H 2 S + 4I 2 + 4H 2 O  [ Balanced Equation ]













  1. Class 10
  2. Chapter 1 Class 10 - Chemical Reactions and Equations (Term 1)

About the Author

CA Maninder Singh's photo - Founder at Teachoo
CA Maninder Singh
CA Maninder Singh is a Chartered Accountant for the past 11 years and a teacher from the past 11 years. He teaches Science, Accounts and English at Teachoo