To remove sodium from water, one may apply reverse osmosis, electro dialysis, distillation techniques or ion exchange. Reverse osmosis is most economical considering energy and money requirements.

Reaction of sodium with water Sodium metal reacts rapidly with water to form a colourless solution of sodium hydroxide (NaOH) and hydrogen gas (H2). The reaction is exothermic. During the reaction, the sodium metal may well become so hot that it catches fire and burns with a characteristic orange colour.

Sodium can not be stored in water because Reaction of sodium and water is highly exothermic. During this reaction hydrogen gas is produces which catches fire due to heat released during reaction. Sodum is a very-very reactive metal.

Only certain metals are flammable and examples of combustible metals include sodium, potassium, uranium, lithium, plutonium and calcium, with the most common Class D fires involve magnesium and titanium.

Sodium is a very reactive metal.It reacts with oxygen to form Sodium Oxide. The reaction produces a lot of heat and it catches fire.It is,therefore, stored in kerosene. Sodium and Potassium combine with oxygen to form their oxiden. The reaction is so vigorous that it catches fire.

Most alkali metals and alkaline earth metals react with water to produce hydrogen. The alkali metals comprise Group 1 of the periodic table, and include lithium, sodium, potassium, rubidium, cesium and francium.

These metals can replace hydrogen from cold water to produce the hydroxide and hydrogen gas: 2K + 2H2O → 2KOH + H2. Somewhat “less active” metals, such as aluminum, magnesium, chromium and zinc, will only react with hot water and will produce the oxide and hydrogen gas: Mg + H2O  MgO + H2.

Reactivity series of metals

Due to its highly negative redox potential, aluminium reacts with water to produce hydrogen gas according to the equation: 2Al + 3H2O → 3H2 + Al2O3. This chemical reaction may be of particular importance when it occurs between the strands of an aluminium conductor.

Removal of aluminium can be carried out by several methods such as cation exchange resin, reverse osmosis and electrodialysis. Treatment methods namely aeration/ Page 2 52 stripping, chemical oxidation/disinfection and anion exchange are ineffective for Al removal.

Copper does not react with water, but it does slowly react with atmospheric oxygen to form a layer of brown-black copper oxide which, unlike the rust that forms on iron in moist air, protects the underlying metal from further corrosion (passivation).

Calcium reacts slowly with water. The reaction forms calcium hydroxide, Ca(OH)2 and hydrogen gas (H2). The calcium metal sinks in water and after an hour or so bubbles of hydrogen are evident, stuck to the surface of the metal.

Magnesium (Mg) reacts with water vapor to form magnesium hydroxide and hydrogen gas. Beryllium (Be) is the only alkaline earth metal that does not react with water. This is due to its small size and high ionization energy in relation to the other elements in the group.

It can be removed by using a water softener which works on the principle of ion exchange in which calcium and magnesium ions are exchanged with sodium or potassium ions, reducing the concentration of hardness minerals to tolerable levels and thus making the water softer and giving it a smoother feeling [2].

When a piece of calcium is dropped in water, it reacts with water and liberates hydrogen in the form of bubbles which brings the calcium upwards and makes it to float.

Calcium Carbide reacts with WATER and MOISTURE to produce flammable Acetylene gas and Lime. The heat of the reaction may ignite the Acetylene.

Calcium, for example, reacts fairly vigorously with cold water in an exothermic reaction. Bubbles of hydrogen gas are given off, and a white precipitate (of calcium hydroxide) is formed, together with an alkaline solution (also of calcium hydroxide – calcium hydroxide is slightly soluble).

The reaction of calcium with water is represented by the equation: Ca+2H2O→Ca(OH)2+H2↑

Calcium oxide