White phosphorus (p4) is a highly reactive, waxy and translucent solid known for its different garlic like odour and spontaneous flammability. Learn about white phosphorus, including its properties, common applications, potential health hazards and effects on the environment.
White phosphorus is a highly reactive, toxic and flammable form of phosphorus that ignites spontaneously in air at roughly 30°C producing intense heat and dense white smoke. It is used in military weapons, fireworks and industrial manufacturing. White Phosphorus causes severe, deep and slow healing chemical burns. The element consists of tetrahedra where four phosphorus atoms are connected in a pyramid shape. The high strain in these bond angles makes it extremely reactive.
What is White Phosphorus?
White phosphorus, also known as yellow phosphorus or tetraphosphorus (P₄), is an allotrope of the element phosphorus. It is a translucent, waxy solid that gradually turns yellow when exposed to light due to its photochemical conversion into red phosphorus. Because of this change in color, impure white phosphorus is often referred to as yellow phosphorus. White phosphorus is one of the three main allotropes of phosphorus. White phosphorus is a very reactive and toxic waxy solid form of phosphorus that glows in the dark and ignites spontaneously in air. It is used primarily in military weapons and smoke screens. This element produces intense heat and thick smoke which is capable of causing severe injuries. It is also known as yellow phosphorus or Willie Pete and is highly toxic if ingested or inhaled as it can cause deep, severe burns to skin and tissue.
Characteristics of White Phosphorus
White phosphorus is a waxy crystalline solid that appears colorless to yellow. It spontaneously ignites in air and produces dense white smoke known as phosphorus pentoxide. It is insoluble in water and requires storage under water. The element is capable of causing severe, deep and fatal thermal and chemical burns. Let’s take a look at the characteristics of white phosphorus: -
- Physical Appearance: White Phosphorus is translucent and waxy solid that turns yellow or darker over time.
- Reactivity: White Phosphorus spontaneously ignites in air to form phosphorus pentoxide and phosphoric acid.
- Melting and Boiling Point: The element melts at 44.15°C and boils at 280.5°C.
- Solubility: It is insoluble in water but soluble in carbon disulfide and organic solvents.
- Toxicity: It is highly toxic to humans and exposure causes severe burns, systemic toxicity, and damage to vital organs.
- Structure: White Phosphorus exists as a tetratomic molecule.
Uses of White Phosphorus
White Phosphorus is used in military weapons, chemical manufacturing and fireworks. It also used to produce phosphoric acid and phosphates to create food additives. The smoke produced by burning phosphorus is harmful to both the eyes and the respiratory system, as it contains phosphoric acids and phosphine gas. Let’s take a look at the uses of white phosphorus: -
1. Military Weapons
White Phosphorus has the ability to spontaneously ignite at 30°C upon contact with air, it is used in grenades, artillery shells and bombs to destroy structures and cause intense fires. It burns to produce dense and white smoke which is highly effective for concealing troop movements.
2. Phosphoric Acid and Phosphates
White Phosphorus is used as a primary raw material for producing phosphoric acid which is important for making fertilizers and food grade additives. Phosphates are also added to animal and poultry feed as a nutrient.
3. Chemical Manufacturing
White Phosphorus is used in the production of phosphorus trichloride, phosphorus oxychloride and phosphorus pentoxide. These substances are utilised to make plastics and fire retardants.
4. Smoke Screens
White phosphorus burns to produce dense and white smoke which is highly effective for concealing military movements from visual and infrared detection. It is also used as a screening agent to cover friendly movement and as a marker for targets.
5. Phosphoric Acid
White phosphorus is widely used in the production of phosphoric acid, an essential industrial chemical. Phosphoric acid is used in fertilizers, food additives, and cleaning agents, playing a crucial role in agriculture, food processing, and various manufacturing processes.
Health Risks of White Phosphorus
White phosphorus is a highly toxic substance which can cause severe health risks through skin contact, inhalation and ingestion. It causes severe dermal burns, causes irritation in the respiratory tract, liver and kidney damage and can also lead to death. Let’s take a look at the health risks of white phosphorus:-
1. Severe Dermal Burns
White phosphorus is lipid-soluble which allows it to penetrate deep into skin and tissues to cause severe slow-healing burns. Particles on the skin can continue to burn and may spontaneously reignite until removed.
2. Acute Ingestion Effects
White Phosphorus ingestion leads to severe vomiting, diarrhea, abdominal pain, liver and kidney damage and coma. It can also lead to potential death within 24 to 48 hours due to complete cardiovascular collapse.
3. Psychological Impact
Survivors of white phosphorus exposure may suffer from severe psychological trauma such as Post Traumatic Stress Disorder due to the intense pain and traumatic nature of the injury. Approximately 68% of survivors develop long-term neuropsychiatric disorders such as insomnia and hypervigilance.
4. Inhalation Hazards
Inhaling white phosphorus smoke causes severe irritation to the eyes and respiratory tract. It can lead to potential fluid accumulation in the lungs known as pulmonary edema, bronchitis and Acute Respiratory Distress Syndrome.
5. Systematic Toxicity
Absorption of phosphorus through burns or ingestion can lead to multiple organ failure, primarily targeting the liver and kidneys. It can also lead to cardiovascular damage and electrocardiogram abnormalities.
Environmental Impact of White Phosphorus
White phosphorus is a very toxic and reactive substance which causes extreme environmental damage such as soil acidification, widespread fire damage to ecosystems, and contamination of water sources.Let’s take a look at the environmental impact of white phosphorus:-
1. Soil and Agriculture
White phosphorus contamination can make agricultural land unusable for generations by killing plants and reducing the fertility of the soil. It leaves behind toxic residue that disrupts soil chemistry which leads to reduced agricultural productivity.
2. Water Contamination
When phosphorus enters water, it can kill fishes and accumulate in their bodies. The element breaks down in water within days but in low oxygen conditions, it can create highly toxic phosphine gas leading to water contamination.
3. Persistent Contamination
While white phosphorus often reacts rapidly with oxygen in the air, it can persist for several years in deeper and oxygen-deprived soil or sediments leading to persistent and prolonged contamination.
4. Wildlife and Biodiversity
White phosphorus contamination can severely harm wildlife and biodiversity. Toxic residues in soil and water affect animals, disrupt food chains, and damage habitats. Aquatic life is especially vulnerable, leading to population decline and long-term ecological imbalance in affected ecosystems. The heat from white phosphorus munitions creates intense, large-scale fires that incinerate vegetation and destroy habitats, harming biodiversity. It is capable of causing reproductive failures in aquatic ecosystems.
5. Toxic By-Products
White phosphorus produces phosphoric acid and other phosphorus oxides which can lead to severe environmental contamination and pollution. In water with low oxygen, white phosphorus can remain unreacted for years leading to severe contamination.
Conclusion
White Phosphorus is a very reactive and toxic form of phosphorus which has many utilities but significant hazards. The element is used in military weapons, smoke screens, chemical manufacturing and in the production of phosphoric acid & phosphates. However, White phosphorus is very dangerous as it can cause severe dermal burns, abdominal pain, liver and kidney damage and coma. It can also lead to death within 24 to 48 hours due to cardiovascular collapse.