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Physical and chemical properties of sodium: appearance,melting point,boiling point,reaction with; air,water,chlorine and ammonia

Answer Text:
Properties of Sodium;
- Is a soft silvery metal with low density; `0.979gcm^(-3)`
- Has a low melting point, `97^oC`, and a low boiling point of `883^oC`.
Chemical reactions
(a) With air
- Na is very reactive and tarnishes in moist air to form an oxide layer.
`4Na(s)+O_2(g) to 2Na_2O(s)`
- The oxide layer reacts with more air moisture to form hydroxide
`Na_2O(s) +CO_2(g) to Na_2CO_3(s) + H_2O(l)`
Note
- Due to those series of reactions sodium is stored under a liquid hydrocarbon e.g. petroleum, kerosene.
- Sodium burns in oxygen with a golden yellow flame to form sodium peroxide
Equation:
`2Na(s) + O_2(g) to Na_2O_2(s)` (White)
(b). With water
- Na reacts vigorously with water to form NaOH and Hydrogen.
Equation:
`2Na(s) + 2H_2O(l) to 2NaOH(aq) + H_2(g)`
- The resulting solution is highly alkaline with a PH of 14.
- Sodium is stored under oil to prevent contact with moisture from the atmosphere.
Note:
- The reaction between Na and dilute acids would beexplosive and not safe to investigate
(c). With chlorine
- Sodium burns in chlorine gas;
`2Na(s) + Cl_2(g) to 2NaCl(s)`
(d) With ammonia gas;
- Sodium forms hydrogen and a solid
`2Na(s) + NH_3(g) to 2NaNH_2(s) + H_2(g)`
Sodamide
And;
`NaNH_2(s) + H_2O(l) to NaOH(aq) + NH_3(g)`