Final answer:
A chemical equation is only balanced when the number of atoms of each element is equal on both sides. While the equation CH4(g) + 2O2(g) → CO₂(g) + 2H₂O(l) is balanced, others like 2Na(s) + O2(g) → 2Na₂O(s) and C₂H₄(g) + 3O₂(g) → 2CO₂(g) + 2H₂O(l) are not because they have mismatched counts of atoms on each side.
Step-by-step explanation:
To determine if a chemical equation is balanced, one must ensure that the number of atoms of each element is the same on both sides of the equation. Let's examine each provided reaction:
- a. 2Na(s) + O₂(g) → 2Na₂O(s) - This equation is not balanced. The left side has 2 sodium atoms while the right side has 4.
- b. CH4(g) + 2O2(g) → CO₂(g) + 2H₂O(l) - This equation is balanced with 1 carbon, 4 hydrogen, and 4 oxygen atoms on both sides.
- c. AgNO3(aq) + 2KCl(aq) → AgCl(s) + KNO3(aq) - This equation is not balanced as written because it lacks a coefficient before KNO3 to balance the potassium (K) and nitrate (NO3) ions.
Other examples provided include:
- b. C₂H₄(g) + 3O₂(g) → 2CO₂(g) + 2H₂O(l) - This equation is not balanced because there is an unbalanced oxygen count.
- d. BaCl₂(aq) + K₂SO4(aq) → BaSO4(s) + 2KCl(aq) - This reaction is balanced with correct stoichiometry on both sides.