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This piece of Potassium has been placed with oil,
without doing this, the metal would oxide
by water or air
Photo Credit: Periodic Table
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Relative Atomic Mass: 39.1
Period: 4
Group: 1
Block: S
Symbol: K
Potassium (See photo: left) is a soft silver metal which swiftly tarnishes when the metal touches air or water. The element is the 7th most abundant metal with the planet crust. Potassium makes up 2.4% by mass.
Most potassium minerals are found within igneous rock - rocks formed from the cooling or soildification of lava or magma. They are soluable or disolve in water in small quanties. Potassium can be difficult to get hold of from these minerals.
There are other minerals where potassium is located. There is Sylvite (Potassium Chloride), Sylvinite (Mix of potassium chloride and sodium Chloride) and carnallite (potassiun magnesium chloride) which are found in deposit formed by evaporation of old seas and lakes. Potassium is much easily taken from these salts.
Discovery of Potassium
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| Photo Credit: Wikipedia |
Although potassium's salts have been known for centuries. These potassium salts were known as; potassium nitrate (saltpetre) (KNO₃), potassium aluminium sulfate (Alum) (KAl(SO₄)₂) and potassium carbonate (potash) (K₂CO₃). These salts were scraped of latrines (Yes, a toilet!), manufactured from clay and sulfuric acid as well as being collected from wood ash. The salts are used to dye as well as make gunpowder and soaps.
They tried to get the pure element a while before Sir Humphry Davy succeeded. But reducing the salt to the pure potassium was difficult for early chemists. Antoine Lavoisier classified potassium as Earth until Sir Humphry Davy isolated the element.
Sir Davy exposed moist potash/potassium carbonate to an electric current - through a procedure called Electrolysis. He observed the formation of metal - the new element, potassium. But then new metal touched the water around it. The metal skimmed across the surface of the water and burnt with a lavender-purple flame - See the Youtube video which I linked for details.
Electrolysis - The technique which uses direct electric current (DC) to drive a non-spontaneous chemical reaction
Biological Uses
Potassium is an element which is essential to life. Potassium ions are found in all cells of the human body. The ion K⁺ is important for maintaining the fluid of the cell and the electroylite balance between the two other main ions in the body - Na⁺ (Sodium) and Ca²⁺ (Calcium). We eat an average of 7 grams of potassium daily and store 140 grams of the element within the body. The average human only needs 3.5 grams of potassium according to the NHS. So the average diet will easily amount to the daily needs of potassium. Especally when there certain foods; coffee, chocolate (See it is good for you), potatoes, sardines and nuts contain a above average concentration of potassium.
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| Photo Credit: Wikipedia |
Plant cells are very rich in potassium which the plant absorbs from the soil. It's essential for plants to have potassium. Therefore, crop fields needs potassium to be enriched back into the soil after every harvest which happens by potassium-enriched fertiliser.
Like all things in chemistry, there are different types of potassium. There is a naturally occurring isotope - same element, just different number of neutrons - which is radioactive!
It's Uses
- Fertiliser - that is the greatest demand of potassium
- The salts - Nitrate, Carbonate, Chlorine, Bromide, Cyanide and Sulfate, have great importance.
- Potassium Carbonate is used in the manufacture of glass
- Potassium hydroxide is used in detergents and soaps
- Potassium Chloride is used in the pharmaceutical business and saline drip
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