Answer:
Na + H₂O → NaOH + 1/2 H₂
Step-by-step explanation:
When sodium reacts with water, it forms sodium hydroxide and molecular hydrogen. The unbalanced equation is:
Na + H₂O → NaOH + H₂
We have to balance this equation so it obeys the law of conservation of mass. We have 1 atom of Na on each side and 1 atom of O on each side, so these elements are balanced. However, we have 2 atoms of H on the left side and 3 atoms of H on the right side. The easiest way to balance the H without modifying the other elements is by making 1/2 the stoichiometric coefficient of H₂.
Na + H₂O → NaOH + 1/2 H₂