Question

what happens when sodium metal is exposed to moist air ?​

Answer 1

Answer:

When sodium is exposed to moist air it forms a coatin of NaO2 and prevents the further reaction of the metal with air. With water it gives NaOH and H2.

Explanation:

Sodium when exposed to air, the surface rapidly tarnishes, darkening at first and then forming a white coating of sodium hydroxide and sodium carbonate. It reacts exothermically with water, to the point that sufficiently large pieces melt to a sphere and may explode; this reaction produces sodium hydroxide and flammable hydrogen gas.

Answer 2

Answer:

Sodium metal first forms sodium oxide then sodium hydroxide and finally form sodium carbonate as final product.

Explanation:

When sodium metal $Na$ is exposed to moist air, it first reacts with oxygen present in air to form a layer of sodium oxide $Na_{2}O$ as:

$4 Na (s) + 2 O_{2} (g)$ → $2Na_{2}O (s)$

Further sodium oxide reacts with the moisture present in the air to form sodium hydroxide $NaOH$ as:

$Na_{2}O (s) + H_{2} O (l)$ → $2 NaOH (aq)$

Sodium hydroxide further also reacts with the carbon dioxide $CO_{2}$ gas present in the air to form sodium carbonate $Na_{2}CO_{3}$ as:

$NaOH (aq) + CO_{2}$  → $Na_{2}CO_{3} (s)$

Therefore the ultimate product formed is sodium carbonate $Na_{2}CO_{3}$.

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