Balancing Chemical Equations - Free Worksheets - Homeschool Den - Free Printable

To solve this problem, we need to balance each chemical equation. This means making sure that the number of atoms for each element is the same on both the left side (reactants) and the right side (products).

Here are the balanced equations with the correct coefficients filled in:

1. $2\text{H}_2 + \text{O}_2 \rightarrow 2\text{H}_2\text{O}$
*(2 Hydrogen molecules react with 1 Oxygen molecule to make 2 Water molecules)*

2. $\text{N}_2 + 3\text{H}_2 \rightarrow 2\text{NH}_3$
*(1 Nitrogen molecule reacts with 3 Hydrogen molecules to make 2 Ammonia molecules)*

3. $\text{S} + \text{O}_2 \rightarrow \text{SO}_2$
*(Already balanced: 1 Sulfur and 2 Oxygens on both sides)*

4. $2\text{C} + \text{O}_2 \rightarrow 2\text{CO}$
*(2 Carbons react with 1 Oxygen molecule to make 2 Carbon Monoxide molecules)*

5. $4\text{Fe} + 3\text{O}_2 \rightarrow 2\text{Fe}_2\text{O}_3$
*(4 Iron atoms react with 3 Oxygen molecules to make 2 Rust molecules)*

6. $2\text{CO}_2 + \text{H}_2\text{O} \rightarrow \text{C}_2\text{H}_2\text{O}_3$ (Note: The product formula in the image is unusual, likely a typo for something else, but balancing strictly for atoms: Left has 2C, 5O, 2H. Right has 2C, 3O, 2H. This specific equation as written $\text{CO}_2 + \text{H}_2\text{O} \rightarrow \text{CH}_2\text{O}_3$ or similar is chemically strange. Let's look closer at #6. It looks like $2\text{CO}_2 + \text{H}_2\text{O} \rightarrow \dots$ actually, looking at standard reactions, it might be photosynthesis simplified or combustion reversed. Let's re-read line 6 carefully. It says `__ CO2 + __ H2O -> __ C6H12O6 + __ O2`. Ah, I see the subscript 6 now. It's photosynthesis.)
*Correction for #6:* $6\text{CO}_2 + 6\text{H}_2\text{O} \rightarrow \text{C}_6\text{H}_{12}\text{O}_6 + 6\text{O}_2$

7. $2\text{K} + 2\text{HCl} \rightarrow 2\text{KCl} + \text{H}_2$
*(2 Potassium atoms react with 2 Hydrochloric acid molecules)*

8. $\text{Ca} + 2\text{HCl} \rightarrow \text{CaCl}_2 + \text{H}_2$
*(1 Calcium atom reacts with 2 Hydrochloric acid molecules)*

9. $\text{Mg} + \text{H}_2\text{SO}_4 \rightarrow \text{MgSO}_4 + \text{H}_2$
*(Already balanced)*

10. $2\text{Na} + 2\text{HCl} \rightarrow 2\text{NaCl} + \text{H}_2$
*(2 Sodium atoms react with 2 Hydrochloric acid molecules)*

11. $\text{NaOH} + \text{HCl} \rightarrow \text{NaCl} + \text{H}_2\text{O}$
*(Already balanced)*

12. $\text{CuO} + 2\text{HCl} \rightarrow \text{CuCl}_2 + \text{H}_2\text{O}$
*(1 Copper Oxide reacts with 2 Hydrochloric acid molecules)*

13. $\text{CaO} + 2\text{HNO}_3 \rightarrow \text{Ca(NO}_3)_2 + \text{H}_2\text{O}$
*(1 Calcium Oxide reacts with 2 Nitric Acid molecules)*

14. $2\text{NaOH} + \text{H}_2\text{SO}_4 \rightarrow \text{Na}_2\text{SO}_4 + 2\text{H}_2\text{O}$
*(2 Sodium Hydroxide react with 1 Sulfuric Acid)*

15. $\text{Al(OH)}_3 + 3\text{HCl} \rightarrow \text{AlCl}_3 + 3\text{H}_2\text{O}$
*(1 Aluminum Hydroxide reacts with 3 Hydrochloric Acid)*

16. $\text{Fe} + \text{Cl}_2 \rightarrow \text{FeCl}_3$ needs balancing.
$2\text{Fe} + 3\text{Cl}_2 \rightarrow 2\text{FeCl}_3$

17. $2\text{NaBr} + \text{Cl}_2 \rightarrow 2\text{NaCl} + \text{Br}_2$
*(2 Sodium Bromide react with 1 Chlorine molecule)*

18. $\text{CaF}_2 + \text{H}_2\text{SO}_4 \rightarrow \text{CaSO}_4 + 2\text{HF}$
*(1 Calcium Fluoride reacts with 1 Sulfuric Acid to make 2 Hydrofluoric Acid)*

19. $\text{CaCO}_3 \rightarrow \text{CaO} + \text{CO}_2$
*(Already balanced: Decomposition of limestone)*

20. $2\text{HgO} \rightarrow 2\text{Hg} + \text{O}_2$
*(2 Mercury(II) Oxide decompose into 2 Mercury and 1 Oxygen molecule)*

21. $2\text{KClO}_3 \rightarrow 2\text{KCl} + 3\text{O}_2$
*(2 Potassium Chlorate decompose into 2 Potassium Chloride and 3 Oxygen molecules)*

22. $2\text{H}_2\text{O}_2 \rightarrow 2\text{H}_2\text{O} + \text{O}_2$
*(2 Hydrogen Peroxide decompose into 2 Water and 1 Oxygen molecule)*

23. $\text{CH}_4 + 2\text{O}_2 \rightarrow \text{CO}_2 + 2\text{H}_2\text{O}$
*(1 Methane reacts with 2 Oxygen molecules)*

24. $\text{C}_2\text{H}_6 + \frac{7}{2}\text{O}_2 \rightarrow 2\text{CO}_2 + 3\text{H}_2\text{O}$ OR using whole numbers:
$2\text{C}_2\text{H}_6 + 7\text{O}_2 \rightarrow 4\text{CO}_2 + 6\text{H}_2\text{O}$

25. $\text{C}_3\text{H}_8 + 5\text{O}_2 \rightarrow 3\text{CO}_2 + 4\text{H}_2\text{O}$
*(1 Propane reacts with 5 Oxygen molecules)*

26. $4\text{Fe} + 3\text{O}_2 \rightarrow 2\text{Fe}_2\text{O}_3$
*(Same as #5)*

Final Answer:
1. $2, 1, 2$
2. $1, 3, 2$
3. $1, 1, 1$
4. $2, 1, 2$
5. $4, 3, 2$
6. $6, 6, 1, 6$
7. $2, 2, 2, 1$
8. $1, 2, 1, 1$
9. $1, 1, 1, 1$
10. $2, 2, 2, 1$
11. $1, 1, 1, 1$
12. $1, 2, 1, 1$
13. $1, 2, 1, 1$
14. $2, 1, 1, 2$
15. $1, 3, 1, 3$
16. $2, 3, 2$
17. $2, 1, 2, 1$
18. $1, 1, 1, 2$
19. $1, 1, 1$
20. $2, 2, 1$
21. $2, 2, 3$
22. $2, 2, 1$
23. $1, 2, 1, 2$
24. $2, 7, 4, 6$ (or $1, 3.5, 2, 3$)
25. $1, 5, 3, 4$
26. $4, 3, 2$