Sodium metal: Physical, Chemistry Property, Manufacture

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Physical properties of sodium

PropertyDescription
State at room temperature and pressureSolid alkali metal
Melting point97.8°C
Boiling point882.9°C
DensityApproximately 0.97 g/cm³
AppearanceSilvery appearance
Reactivity in airOxidizes rapidly to form greyish sodium oxide
HardnessSoft, can be cut with a knife or crushed by fingers
Thermal, electrical conductivityGood, it’s also used in nuclear power plants when mixed with potassium

Chemical properties of sodium.

It has 11 electrons. The outermost shell has only one electron that other elements take away easily. Thus, sodium can react with substances or be oxidized vigorously.

Reaction of sodium with oxygen

Shiny metallic sodium reacts gradually with oxygen to form a thin layer of dull and grayish sodium oxide (Na₂O) on its surface at room temperature.

4Na(s) + O₂(g) → 2Na₂O(s)

If sodium burns in adequate oxygen, it produces a bright yellow flame that leaves sodium peroxide (Na₂O₂) as final product.

2Na(s) + O₂(g) → Na₂O₂(s)

Reaction of sodium with chlorine

It’s so exothermic that explodes in contact with chlorine gas, and the product is table salt or sodium chloride. This’s a classic redox reaction. The highly electronegative chlorine steals one electron from sodium atom during reaction.

2Na(s) + Cl₂(g) → 2NaCl(s)

Reaction of sodium with alcohol

Hydrogen atom in alcohol molecule is displaced by sodium. This reaction isn’t very violent compared to reaction of sodium and water. The most difference is that sodium sinks at bottom and hydrogen bubbles kept rising upward, because it’s denser than alcohol.

2R-OH(l) + 2Na(s) → 2R-O-Na(aq) + H₂(g)

R represents an organic group or alkyl group.

Reaction of sodium with water

When you put a small piece of sodium in a beaker contains water and phenolphthalein, the following phenomenon will be observed by you. The less denser sodium metal will float on water surface. Heat from violent reaction melt metal into a small liquid sphere that moves on water surface as the releasing hydrogen gas. Its size reduces continuously until disappears completely. Phenolphthalein solution becomes pink because of sodium hydroxide.

2Na(s) + 2H₂O(l) → 2NaOH(aq) + H₂(g)

Since it’s one of highly reactive metals, a glass bottle filled with kerosene is used to isolate it from air and water in laboratory.

Frequently Asked Questions

Where is the sodium distributed on Earth?

Sodium is the 6th abundant elements on Earth and 2.8 percent crust is composed by it. It has wide distribution in several natural sources.

Elementary sodium occurs in the form of sodium chloride or table salt in seawater and saltwater lakes. You can obtain it by direct evaporation of salt water. It’s also present in various ores in earth crust. The most familiar one is halite (NaCl) or rock salt. There are a few other ores comprising some sodium carbonate (Na₂CO₃), sodium nitrate (NaNO₃) and various silicates. It can also be found in soil, although the concentration varies according to location and geological conditions. Some soil with high sodium levels is called saline or alkaline soils that ultimately affect plant growth.

How is pure sodium made?

2NaCl(l) → 2Na(l) + Cl₂(g)

The strong reductive sodium is difficult to be extracted by other reducing agents. Engineers devise electrolysis of molten sodium chloride for industrial production. The anode is made of carbon, while iron is main content in cathode. Melted sodium chloride conducts electric current. At negative electrode, sodium ions gain electrons to be liquid metal that floats on electrolyte surface. Chlorine gas accumulates at positive electrode as chlorine ions lose electrons. It is taken out as a by-product. Electrolysis is promoted by a little calcium chloride that lowers NaCl melting point to about 500°C.

Anec  > Chemistry > Alkali metal

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