Balancing chemical equations (KS3/GCSE) – Answers
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1. 2O
2
+ NH
3
-> HNO
3
+ H
2
O
2. 3O
2
-> 2O
3
3. 2H
2
O
2
-> 2H
2
O + O
2
4. 2Rb + 2H
2
O -> 2RbOH + H
2
5. Cl
2
+ 2KBr -> 2KCl + Br
2
6. N
2
+ 3H
2
-> 2NH
3
7. 2NdF
3
+ 3Ca -> 2Nd + 3CaF
2
8. CH
4
+ H
2
O -> CO + 3H
2
9. C
2
H
5
OH + 3O
2
-> 2CO
2
+ 3H
2
O
10. 2Al + Fe
2
O
3
-> 2Fe + Al
2
O
3
11. 2HCl + Ca(OH)
2
-> CaCl
2
+ 2H
2
O
12. 2HNO
3
+ CaCO
3
-> Ca(NO
3
)
2
+ CO
2
+ H
2
O
13. 4Al + 3O
2
-> 2Al
2
O
3
14. 2P + 3Cl
2
-> 2PCl
3
15. P
4
+ 5O
2
-> 2P
2
O
5
16. POCl
3
+ 3H
2
O -> H
3
PO
4
+ 3HCl
17. 3PCl
5
+ P
2
O
5
-> 5POCl
3
18. Fe
2
O
3
+ 3H
2
-> 2Fe + 3H
2
O
Balancing chemical equations (KS3/GCSE) – Answers
© www.chemistrytutor.me 2018 Page 2 of 3
19. P
4
O
6
+ 6H
2
O -> 4H
3
PO
3
20. V
2
O
5
+ 6HCl -> 2VOCl
3
+ 3H
2
O
21. 3Fe + 4H
2
O -> Fe
3
O
4
+ 4H
2
22. C
3
H
6
+ 3O
2
-> 3CO + 3H
2
O
23. Ca
3
(PO
4
)
2
+ 8C -> Ca
3
P
2
+ 8CO
24. S
8
+ 12O
2
-> 8SO
3
25. C
3
H
8
+ 5O
2
-> 3CO
2
+ 4H
2
O
26. 6CoO + O
2
-> 2Co
3
O
4
27. 2C
3
H
6
O
2
+ 7O
2
-> 6CO
2
+ 6H
2
O
28. 2C
3
H
4
+ 5O
2
-> 6CO + 4H
2
O
29. 4LiH + AlCl
3
-> LiAlH
4
+ 3LiCl
30. 2Pb(NO
3
)
2
-> 2PbO + 4NO
2
+ O
2
31. 2Cu(CN)
2
-> 2CuCN + C
2
N
2
32. PCl
3
+ 3H
2
O -> P(OH)
3
+ 3HCl
33. 3KBr + Al(ClO
4
)
3
-> AlBr
3
+ 3KClO
4
34. C
2
H
5
OH + 2O
2
-> 2CO + 3H
2
O
35. 4HCl + MnO
2
-> MnCl
2
+ 2H
2
O + Cl
2
36. 2CrO
4
2-
+ 2H
+
-> Cr
2
O
7
2-
+ H
2
O
37. 4OH
-
-> 2H
2
O + O
2
+ 4e
-
Balancing chemical equations (KS3/GCSE) – Answers
© www.chemistrytutor.me 2018 Page 3 of 3
38. Fe
2
O
3
+ 3CO -> 2Fe + 3CO
2
39. 2H
3
PO
4
+ 3BaO -> Ba
3
(PO
4
)
2
+ 3H
2
O
40. 2MgNH
4
PO
4
-> Mg
2
P
2
O
7
+ 2NH
3
+ H
2
O
41. 2Al + 3H
2
SO
4
-> Al
2
(SO
4
)
3
+ 3H
2
42. P
4
O
10
+ 3HCl -> POCl
3
+ 3HPO
3
43. 4NO + 2H
2
O + 3O
2
-> 4HNO
3
44. Br
2
+ 2NaOH -> NaBr + NaOBr + H
2
O
45. Ca
3
(PO
4
)
2
+ 4H
3
PO
4
-> 3Ca(H
2
PO
4
)
2
46. 3FeSO
4
+ 2K
3
[Fe(CN)
6
] -> Fe
3
[Fe(CN)
6
]
2
+ 3K
2
SO
4
47. 2CuSO
4
+ 4KCN -> 2CuCN + 2K
2
SO
4
+ C
2
N
2
48. CaHPO
4
.2H
2
O + 2NaOH + 10H
2
O -> Na
2
HPO
4
.12H
2
O + Ca(OH)
2
49. 2MgNH
4
AsO
4
.6H
2
O -> Mg
2
As
2
O
7
+ 2NH
3
+ 13H
2
O
50. Mg
3
Si
2
O
5
(OH)
4
+ 3CO
2
-> 3MgCO
3
+ 2SiO
2
+ 2H
2
O
