To determine which equation is balanced, let's examine each option:
-
NaOH + 2HCl → NaCl + H₂O
- Left: 1 Na, 1 O, 2 Cl, 1 H (from NaOH and 2 HCl)
- Right: 1 Na, 1 Cl, 2 H, 1 O (from NaCl and H₂O)
- Not balanced (Cl is not balanced).
-
NaOH + HCl → NaCl + H₂O
- Left: 1 Na, 1 O, 1 Cl, 1 H (from NaOH and HCl)
- Right: 1 Na, 1 Cl, 2 H, 1 O (from NaCl and H₂O)
- Not balanced (H is not balanced).
-
2NaOH + HCl → NaCl + H₂O
- Left: 2 Na, 2 O, 1 Cl, 2 H (from 2 NaOH and HCl)
- Right: 1 Na, 1 Cl, 2 H, 1 O (from NaCl and H₂O)
- Not balanced (Na is not balanced).
-
2NaOH + 2HCl → 2NaCl + 2H₂O
- Left: 2 Na, 2 O, 2 Cl, 4 H (from 2 NaOH and 2 HCl)
- Right: 2 Na, 2 Cl, 4 H, 2 O (from 2 NaCl and 2 H₂O)
- Balanced (both sides have 2 Na, 2 Cl, 4 H, and 2 O).
Therefore, the balanced equation is:
2NaOH + 2HCl → 2NaCl + 2H₂O.