Balancing Equations - Alkali Metals

IGCSE Edexcel Chemistry
Fill in the missing coefficients to balance each equation
Instructions: Each equation below has the formulas already written. Fill in the missing coefficients (the numbers in front of each compound) to balance the equation. Remember: the number of atoms of each element must be the same on both sides.

Section A: Easy - Sodium and Lithium with Oxygen

1.
Na + O₂ → Na₂O
2.
Li + O₂ → Li₂O
3.
K + O₂ → K₂O

Section B: Easy - Simple Reactions with Water

4.
Li + H₂O → LiOH + H₂
5.
Na + H₂O → NaOH + H₂
6.
K + H₂O → KOH + H₂

Section C: Medium - Various Alkali Metals with Oxygen

7.
Rb + O₂ → Rb₂O
8.
Cs + O₂ → Cs₂O
9.
Rb + H₂O → RbOH + H₂
10.
Cs + H₂O → CsOH + H₂

Section D: Medium - Metal Oxides Reacting with Water

11.
Li₂O + H₂O → LiOH
12.
Na₂O + H₂O → NaOH
13.
K₂O + H₂O → KOH

Section E: Harder - Peroxide Formation

14.
Na + O₂ → Na₂O₂
15.
K + O₂ → K₂O₂
16.
Rb + O₂ → Rb₂O₂

Section F: Harder - Mixed Reactions

17.
Li + O₂ → Li₂O₂
18.
Na₂O₂ + H₂O → NaOH + H₂O₂
19.
K₂O₂ + H₂O → KOH + H₂O₂

Section G: Challenge

20.
Cs + O₂ → Cs₂O₃ (superoxide)

Total: 20 equations

Mark Scheme

Section A: Easy - Sodium and Lithium with Oxygen
1. 4 Na + O₂ → 2 Na₂O
2. 4 Li + O₂ → 2 Li₂O
3. 4 K + O₂ → 2 K₂O
Section B: Easy - Simple Reactions with Water
4. 2 Li + 2 H₂O → 2 LiOH + H₂
5. 2 Na + 2 H₂O → 2 NaOH + H₂
6. 2 K + 2 H₂O → 2 KOH + H₂
Section C: Medium - Various Alkali Metals with Oxygen
7. 4 Rb + O₂ → 2 Rb₂O
8. 4 Cs + O₂ → 2 Cs₂O
9. 2 Rb + 2 H₂O → 2 RbOH + H₂
10. 2 Cs + 2 H₂O → 2 CsOH + H₂
Section D: Medium - Metal Oxides Reacting with Water
11. Li₂O + H₂O → 2 LiOH
12. Na₂O + H₂O → 2 NaOH
13. K₂O + H₂O → 2 KOH
Section E: Harder - Peroxide Formation
14. 2 Na + O₂ → Na₂O₂
15. 2 K + O₂ → K₂O₂
16. 2 Rb + O₂ → Rb₂O₂
Section F: Harder - Mixed Reactions
17. 2 Li + O₂ → Li₂O₂
18. 2 Na₂O₂ + 2 H₂O → 4 NaOH + O₂
19. 2 K₂O₂ + 2 H₂O → 4 KOH + O₂
Section G: Challenge
20. 4 Cs + O₂ → 2 Cs₂O₃