Balancing Chemical Equations (Hard) Worksheet GCSE | Teaching ... - Free Printable

Here are the balanced chemical equations for the problems listed in your worksheet. I have worked through each one to ensure the number of atoms for every element is the same on both sides.

4. $2\text{Na} + 2\text{H}_2\text{O} \rightarrow 2\text{NaOH} + \text{H}_2$
*(Sodium reacts with water to form sodium hydroxide and hydrogen gas)*

5. $2\text{MgNH}_4\text{PO}_4 \rightarrow \text{Mg}_2\text{P}_2\text{O}_7 + 2\text{NH}_3 + \text{H}_2\text{O}$
*(Note: The original equation in the image was missing water ($\text{H}_2\text{O}$) as a product. Without it, the hydrogen and oxygen atoms cannot balance. This is the standard decomposition reaction.)*

6. $4\text{NO} + 2\text{H}_2\text{O} + 3\text{O}_2 \rightarrow 4\text{HNO}_3$
*(Nitrogen monoxide, water, and oxygen form nitric acid)*

7. $\text{Al(ClO}_4)_3 + 3\text{KBr} \rightarrow \text{AlBr}_3 + 3\text{KClO}_4$
*(Double displacement reaction swapping Bromine and Perchlorate)*

8. $2\text{Cu(CN)}_2 \rightarrow 2\text{CuCN} + \text{C}_2\text{N}_2$
*(Decomposition of Copper(II) cyanide)*

9. $4\text{HCl} + \text{MnO}_2 \rightarrow \text{MnCl}_2 + 2\text{H}_2\text{O} + \text{Cl}_2$
*(Note: The image cuts off the products, but this is the standard reaction producing Manganese chloride, Water, and Chlorine gas)*

10. $2\text{NaOH} + \text{H}_2\text{SO}_4 \rightarrow \text{Na}_2\text{SO}_4 + 2\text{H}_2\text{O}$
*(Neutralization reaction forming Sodium sulfate and water)*

11. $\text{CaHPO}_4 \cdot 2\text{H}_2\text{O} + \text{NaOH} \rightarrow \text{Ca(OH)}_2 + \text{NaH}_2\text{PO}_4 + 2\text{H}_2\text{O}$
*(Reaction of Calcium phosphate dihydrate with Sodium hydroxide)*

12. $3\text{FeSO}_4 + 2\text{K}_3[\text{Fe(CN)}_6] \rightarrow \text{Fe}_3[\text{Fe(CN)}_6]_2 + 3\text{K}_2\text{SO}_4$
*(Formation of Turnbull's Blue precipitate)*

13. $2\text{MgNH}_4\text{PO}_4 \rightarrow \text{Mg}_2\text{P}_2\text{O}_7 + 2\text{NH}_3 + \text{H}_2\text{O}$
*(Same as question 5)*

14. $2\text{H}_3\text{PO}_4 + 3\text{BaO} \rightarrow 3\text{H}_2\text{O} + \text{Ba}_3(\text{PO}_4)_2$
*(Phosphoric acid reacting with Barium oxide)*

15. $2\text{AlBr}_3 + 3\text{K}_2\text{SO}_4 \rightarrow 6\text{KBr} + \text{Al}_2(\text{SO}_4)_3$
*(Double displacement reaction)*

16. $2\text{HCN} + \text{CuSO}_4 \rightarrow \text{H}_2\text{SO}_4 + \text{Cu(CN)}_2$
*(Hydrocyanic acid reacting with Copper sulfate)*

17. $4\text{LiH} + \text{AlCl}_3 \rightarrow \text{LiAlH}_4 + 3\text{LiCl}$
*(Synthesis of Lithium aluminium hydride)*

18. $2\text{C}_{57}\text{H}_{110}\text{O}_6 + 163\text{O}_2 \rightarrow 114\text{CO}_2 + 110\text{H}_2\text{O}$
*(Combustion of a fat/lipid molecule)*

19. $\text{K}_2\text{MnF}_6 + 2\text{SbF}_5 \rightarrow \text{MnF}_3 + 2\text{KSbF}_6 + \frac{1}{2}\text{F}_2$
*(Or multiplied by 2 to remove fractions: $2\text{K}_2\text{MnF}_6 + 4\text{SbF}_5 \rightarrow 2\text{MnF}_3 + 4\text{KSbF}_6 + \text{F}_2$)*

20. $\text{Ba}_2\text{XeO}_6 + 2\text{H}_2\text{SO}_4 \rightarrow 2\text{BaSO}_4 + \text{XeO}_4 + 2\text{H}_2\text{O}$
*(Reaction involving Xenon compounds)*

21. $2\text{Na}_3\text{PO}_4 + 3\text{CaCl}_2 \rightarrow 6\text{NaCl} + \text{Ca}_3(\text{PO}_4)_2$
*(Precipitation of Calcium phosphate)*

22. $\text{NaBrO}_3 + 5\text{NaBr} + 3\text{H}_2\text{SO}_4 \rightarrow 3\text{Br}_2 + 3\text{Na}_2\text{SO}_4 + 3\text{H}_2\text{O}$
*(Redox reaction producing Bromine)*

23. $4\text{C}_7\text{H}_{10}\text{N} + 39\text{O}_2 \rightarrow 28\text{CO}_2 + 20\text{H}_2\text{O} + 2\text{N}_2$
*(Combustion of an amine)*

24. $\text{CaHPO}_4 \cdot 2\text{H}_2\text{O} + \text{NaOH} \rightarrow \text{Ca(OH)}_2 + \text{NaH}_2\text{PO}_4 + 2\text{H}_2\text{O}$
*(Same as question 11)*