50 Balancing Chemical Equation Worksheet - Free Printable

To balance chemical equations, we need to make sure that the number of atoms for each element is the same on both the left side (reactants) and the right side (products). We do this by adding numbers (coefficients) in front of the chemical formulas. We cannot change the small numbers inside the formulas (subscripts).

Here is the step-by-step solution for each equation:

1. Na + Cl₂ → NaCl
* Left: 1 Na, 2 Cl
* Right: 1 Na, 1 Cl
* To balance Chlorine (Cl), put a 2 in front of NaCl. Now we have 2 Na on the right.
* To balance Sodium (Na), put a 2 in front of Na on the left.
* Balanced: 2Na + Cl₂ → 2NaCl

2. Mg + HCl → MgCl₂ + H₂
* Left: 1 Mg, 1 H, 1 Cl
* Right: 1 Mg, 2 H, 2 Cl
* Magnesium (Mg) is already balanced.
* To balance Hydrogen (H) and Chlorine (Cl), put a 2 in front of HCl.
* Balanced: Mg + 2HCl → MgCl₂ + H₂

3. H₂ + O₂ → H₂O
* Left: 2 H, 2 O
* Right: 2 H, 1 O
* To balance Oxygen (O), put a 2 in front of H₂O. Now we have 4 H on the right.
* To balance Hydrogen (H), put a 2 in front of H₂ on the left.
* Balanced: 2H₂ + O₂ → 2H₂O

4. Fe + Cl₂ → FeCl
* Left: 1 Fe, 2 Cl
* Right: 1 Fe, 3 Cl
* The least common multiple for Chlorine (2 and 3) is 6.
* Put a 3 in front of Cl₂ (to get 6 Cl) and a 2 in front of FeCl₃ (to get 6 Cl).
* Now we have 2 Fe on the right, so put a 2 in front of Fe on the left.
* Balanced: 2Fe + 3Cl₂ → 2FeCl₃

5. H₂O₂ → O₂ + H₂O
* Left: 2 H, 2 O
* Right: 2 H, 3 O (2 from O₂ + 1 from H₂O)
* To balance Oxygen, let's try putting a 2 in front of H₂O. Now the right side has 2 H and 4 O total? No, wait.
* Right side with 2H₂O: 4 H and 2 O (from water) + 2 O (from gas) = 4 H and 4 O.
* Left side needs 4 H and 4 O. Put a 2 in front of H₂O₂.
* Balanced: 2H₂O₂ → O₂ + 2H₂O

6. Ca + H₂O → Ca(OH)₂ + H₂
* Left: 1 Ca, 2 H, 1 O
* Right: 1 Ca, 4 H (2 in OH group + 2 gas), 2 O
* Calcium (Ca) is balanced.
* To balance Oxygen and Hydrogen, put a 2 in front of H₂O. This gives 4 H and 2 O on the left.
* Balanced: Ca + 2H₂O → Ca(OH)₂ + H₂

7. Ca + HNO → Ca(NO₃)₂ + H₂
* Left: 1 Ca, 1 H, 1 N, 3 O
* Right: 1 Ca, 2 H, 2 N, 6 O (inside the two nitrate groups)
* It is easier to treat the nitrate group (NO₃) as one unit.
* There are 2 nitrate groups on the right, so put a 2 in front of HNO₃.
* This gives 2 H on the left, which matches the H₂ on the right.
* Balanced: Ca + 2HNO₃ → Ca(NO₃)₂ + H₂

8. Ca + H₃PO₄ → Ca₃(PO₄)₂ + H₂
* Left: 1 Ca, 3 H, 1 P, 4 O
* Right: 3 Ca, 2 H, 2 P, 8 O
* Balance Calcium (Ca) first: Put a 3 in front of Ca on the left.
* Balance Phosphate (PO): There are 2 groups on the right, so put a 2 in front of H₃PO₄ on the left.
* Check Hydrogen: Left has 2 × 3 = 6 H. Right has H₂. To get 6 H, put a 3 in front of H₂.
* Balanced: 3Ca + 2H₃PO₄ → Ca₃(PO₄)₂ + 3H₂

Final Answer:
1. 2Na + Cl₂ → 2NaCl
2. Mg + 2HCl → MgCl₂ + H₂
3. 2H₂ + O₂ → 2H₂O
4. 2Fe + 3Cl₂ → 2FeCl₃
5. 2H₂O₂ → O₂ + 2H₂O
6. Ca + 2H₂O → Ca(OH)₂ + H₂
7. Ca + 2HNO₃ → Ca(NO₃)₂ + H₂
8. 3Ca + 2H₃PO₄ → Ca₃(PO₄)₂ + 3H₂