To determine which equation is balanced, we need to ensure that the number of atoms of each element is the same on both sides of the reaction for each equation. Let's analyze each one:
-
Mg3N2 + H2O → 3MgO + 2NH3
- Left: 3 Mg, 2 N, 2 H (from H2O), 1 O
- Right: 3 Mg, 2 N (from 2NH3), 6 H (from 2NH3), 3 O
- Not balanced.
-
C3H8 + 5O2 → H2O + 3CO2
- Left: 3 C, 8 H, 10 O
- Right: 3 C (from 3CO2), 2 H (from H2O), 6 O (from 3CO2), 1 O (from H2O)
- Not balanced.
-
Zn + 2HCl → ZnCl2 + H2
- Left: 1 Zn, 2 H, 2 Cl
- Right: 1 Zn, 2 Cl (from ZnCl2), 2 H
- Balanced!
-
3H2SO4 + 2Fe → Fe2(SO4)3 + H2
- Left: 6 H, 3 S, 8 O, 2 Fe
- Right: 2 Fe, 3 S (from Fe2(SO4)3), 12 O (from 3 SO4), 2 H
- Not balanced.
The only equation that is balanced is:
Zn + 2HCl → ZnCl2 + H2.