All About Fluorine (F)
Physical Properties
Fluorine is found in nature as a diatomic molecule (difluorine). Under standard conditions (STP), fluorine is a pale yellow gas. Fluorine gas is very harmful to humans because it is highly toxic.
Fluorine is the most reactive element of all the elements present in the periodic table. Because it is highly reactive, fluorine is dubbed as "Tyrannosaurus rex".
The proof of fluorine reactivity is that it can react with every element in the periodic table, except for helium, neon, and argon. The three elements that do not react with the fluorine are noble gas elements.
In addition, fluorine cannot be found in its elemental form in nature. Fluorine always binds with other elements to achieve stability.
Fluorine elements are single-bonded to form diatomic molecules of difluorine (F2). The bond energy between F - F in difluorine is the weakest of all the single bonds in the diatomic molecules of other halogen elements.
This weak bond is easily broken to cause a chemical reaction. This is the reason why fluorine is so reactive.
However, when forming covalent compounds with other elements, the bonds are very strong. For example, the F-F bond energy is only 155 kJ / mol, while the C-F bond energy (in carbon tetrafluoride) is 485 kJ / mol.
The difference in bond strength is due to the lattice energy possessed by the fluoride ion is very high. This high lattice energy is caused by small fluoride ions while the charge density is high.
Chemical Properties
Reacting an element with fluorine gas will be produced a product where the element exists in the highest oxidation state. For example, the iron powder will burn if reacted with a fluorine gas producing iron (III) fluoride, not iron (II) fluoride.
2Fe (s) + 3F2 (g) ==> 2FeF3 (s)
Another example, sulfur also burns to produce bright flame and sulfur hexafluoride compounds when reacted with fluorine gas.
S (s) + 3 F3 (g) ==> SF6 (g)
Fluorine gases can also oxidize uranium (IV) fluoride to uranium (VI) fluoride.
UF4 (s) + F2 (g) ==> UF6 (g)
From some examples above, it is evident that fluorine has a strong oxidizing power.
When reacted with water, fluorine can oxidize water to oxygen gas. But simultaneously fluorine is also reduced to fluoride ions.
Reduction: F2 (g) + 2e ==> 2F- (aq)
Oxidation: 2 H2O (l) ==> 4H + (aq) + O2 (g) + 4e
Preparation Of Fluorine
Difluorine is made using Moissan electrolysis method. Moissan was the first chemist that discover and synthesize fluorine with his electrolysis device. This method has been used to produce fluorine for more than 100 years since it was first discovered in 1886.
The electrolytic cell that used to produce fluorine gas can be laboratory-size, running at currents between 10 A to 50 A. It also can be industrial-size where it running at currents up to 15.000 A.
Inside the cell, there is a molten mixture of potassium fluoride (KF) and hydrogen fluoride (HF) with 1: 2 ratio. The cell is running at 90 deg Celcius. To make the temperature constant, outside of the cell is installed a jacket to heat up the cell initially and then to cool it as the exothermic electrolysis occurs.
At the center of the cell, there is a carbon as the anode. The wall of the apparatus is made from steel and act as the cathode. In anode, fluoride ions will oxidize to fluorine while in the cathode, hydrogen gas is produced.
2F-(g) ==> F2(g) + 2e
2H+(g) + 2e ==> H2(g)
Hydrogen fluoride gas must be bubbled into the cell continuously to replace that used in the process. Annual productions of fluorine gas are at least 10^4 tonnes and 55 percent of them is used to prepared uranium(VI)fluoride.
Uses of Fluorine
Fluorine is found in nature as a diatomic molecule (difluorine). Under standard conditions (STP), fluorine is a pale yellow gas. Fluorine gas is very harmful to humans because it is highly toxic.
Fluorine is the most reactive element of all the elements present in the periodic table. Because it is highly reactive, fluorine is dubbed as "Tyrannosaurus rex".
The proof of fluorine reactivity is that it can react with every element in the periodic table, except for helium, neon, and argon. The three elements that do not react with the fluorine are noble gas elements.
In addition, fluorine cannot be found in its elemental form in nature. Fluorine always binds with other elements to achieve stability.
Fluorine elements are single-bonded to form diatomic molecules of difluorine (F2). The bond energy between F - F in difluorine is the weakest of all the single bonds in the diatomic molecules of other halogen elements.
This weak bond is easily broken to cause a chemical reaction. This is the reason why fluorine is so reactive.
However, when forming covalent compounds with other elements, the bonds are very strong. For example, the F-F bond energy is only 155 kJ / mol, while the C-F bond energy (in carbon tetrafluoride) is 485 kJ / mol.
The difference in bond strength is due to the lattice energy possessed by the fluoride ion is very high. This high lattice energy is caused by small fluoride ions while the charge density is high.
Chemical Properties
Reacting an element with fluorine gas will be produced a product where the element exists in the highest oxidation state. For example, the iron powder will burn if reacted with a fluorine gas producing iron (III) fluoride, not iron (II) fluoride.
2Fe (s) + 3F2 (g) ==> 2FeF3 (s)
Another example, sulfur also burns to produce bright flame and sulfur hexafluoride compounds when reacted with fluorine gas.
S (s) + 3 F3 (g) ==> SF6 (g)
Fluorine gases can also oxidize uranium (IV) fluoride to uranium (VI) fluoride.
UF4 (s) + F2 (g) ==> UF6 (g)
From some examples above, it is evident that fluorine has a strong oxidizing power.
When reacted with water, fluorine can oxidize water to oxygen gas. But simultaneously fluorine is also reduced to fluoride ions.
Reduction: F2 (g) + 2e ==> 2F- (aq)
Oxidation: 2 H2O (l) ==> 4H + (aq) + O2 (g) + 4e
Preparation Of Fluorine
Difluorine is made using Moissan electrolysis method. Moissan was the first chemist that discover and synthesize fluorine with his electrolysis device. This method has been used to produce fluorine for more than 100 years since it was first discovered in 1886.
The electrolytic cell that used to produce fluorine gas can be laboratory-size, running at currents between 10 A to 50 A. It also can be industrial-size where it running at currents up to 15.000 A.
Inside the cell, there is a molten mixture of potassium fluoride (KF) and hydrogen fluoride (HF) with 1: 2 ratio. The cell is running at 90 deg Celcius. To make the temperature constant, outside of the cell is installed a jacket to heat up the cell initially and then to cool it as the exothermic electrolysis occurs.
At the center of the cell, there is a carbon as the anode. The wall of the apparatus is made from steel and act as the cathode. In anode, fluoride ions will oxidize to fluorine while in the cathode, hydrogen gas is produced.
2F-(g) ==> F2(g) + 2e
2H+(g) + 2e ==> H2(g)
Hydrogen fluoride gas must be bubbled into the cell continuously to replace that used in the process. Annual productions of fluorine gas are at least 10^4 tonnes and 55 percent of them is used to prepared uranium(VI)fluoride.
Uses of Fluorine
- In small quantities, fluoride ions are added to the toothpaste because they can strengthen tooth enamel. But according to research, fluoride ions can turn the color of the teeth into brown.
- Fluor is used to making CFC compounds (chlorofluorocarbons). CFC is widely used as a refrigerant (AC or refrigerator) and propellant.
- Fluorine is an essential ingredient to make fluoroethane. Fluoroethane is a monomer for making Teflon that is a nonstick material on cooking utensils.
- Fluorine is used to make SF6 gas used as a dielectric medium.
- Fluorine is used in the manufacture of aluminum fluoride and cryolite compounds.
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