Interaction of sodium with various substances

Chemical properties of sodium

[Deposit Photos]

Sodi­um is an al­ka­line met­al in the first group and third pe­ri­od. In pure form it has a sil­very col­or with a metal­lic shine, is not hard (can be cut with a knife), melts at a tem­per­a­ture of 97.8°С, and has a den­si­ty of around 0.97 g/cm³.


Gen­er­al char­ac­ter­is­tics of sodi­um

Sodi­um has a high ac­tiv­i­ty and the abil­i­ty to en­ter into a re­ac­tion vi­o­lent­ly and quick­ly with many sub­stances.

Sodi­um is one of the el­e­ment that makes up an­i­mal and plant cells. The el­e­ment is found in high con­cen­tra­tion in sea wa­ter. Sodi­um is present in sev­er­al min­er­als, for ex­am­ple sylvi­nite (NaCl·KCl). Sylvi­nite has a het­eroge­nous struc­ture with parts of dif­fer­ent col­ors, in­clud­ing pink, or­ange, red and blue. Sylvi­nite is ful­ly sol­u­ble in wa­ter.

Sylvinite [Deposit Photos]

How to work with sodi­um in the lab­o­ra­to­ry

In the air, sodi­um swift­ly ox­i­dizes, and be­comes cov­ered with a gray film, so the met­al is stored in sealed jars un­der a lay­er of oil or wa­ter­less kerosene. A piece of sodi­um of re­quired size is cut with a scalpel or knife, with­out tak­ing the met­al out of the kerosene. Sodi­um is tak­en out of the jar with tweez­ers. All tools must be dry — this is a com­pul­so­ry con­di­tion. The met­al must not be picked up with bare hands. The con­tain­er sodi­um is kept in must not be washed with wa­ter – this may cause an ex­plo­sion. The re­mains of sodi­um are re­moved by adding al­co­hol to them, and then wa­ter can be used to wash the con­tain­er. You must wear pro­tec­tive glass­es when work­ing with sodi­um.

Here you’ll find safe ex­per­i­ments with sodi­um com­pounds.

Re­ac­tion of sodi­um with var­i­ous sub­stances

Sodi­um en­ters into a re­ac­tion with all halo­gens — io­dine, flu­o­rine, bromine and chlo­rine, form­ing sodi­um io­dide, flu­o­ride, bro­mide and chlo­ride re­spec­tive­ly.

Sodium bromide [Wikimedia]

Sodi­um can also re­act with phos­pho­rus, sul­fur and car­bon. Chem­i­cal in­ter­ac­tions of this kind main­ly take place at high tem­per­a­ture.

Sodi­um en­ters into a re­ac­tion with acids. When sodi­um re­acts with di­lut­ed hy­drochlo­ric acid, sodi­um chlo­ride and hy­dro­gen form. The equa­tion of the re­ac­tion:

Na + HCl = NaCl + Н₂

When sodi­um and wa­ter in­ter­act, sodi­um hy­drox­ide (caus­tic soda) forms. Sodi­um floats to the sur­face, as it is lighter than wa­ter. The ac­tive re­ac­tion of sodi­um with wa­ter takes place, with the re­lease of hy­dro­gen. From the heat of the re­ac­tion, the met­al melts and turns into a sil­very drop, which darts across the sur­face of the wa­ter and makes a hiss­ing sound. Some­times the hy­dro­gen re­leased burns with a yel­low flame. The equa­tion of the re­ac­tion:

2Na + 2H₂O = 2NaOH + H₂