What is Phosphide Definition Types Formation Reactions and Uses
Very simply, phosphide is a compound of phosphorus of a binary nature. It has a more electropositive element or group of elements in it. When in any chemical compound phosphorous is combined or used with metal, the phosphide ion is always P3-. The phosphides of all the metals of the periodic table are known. The phosphides of these metals show different types of physical and chemical properties.
Phosphides can be prepared in various ways, one of which is by heating any metal of stoichiometric amount with red phosphorous at high temperatures in a chemically inactive or inert environment. This process also works if the process is conducted inside a vacuum.
Phosphides can be of many different types with their own physical and chemical properties. This is the reason why phosphides can not be appropriately placed in classes. With the basic knowledge of what phosphides are, let’s learn about the different types of phosphides.
What is Silver Phosphide?
The molecular formula of silver phosphide is Ag3P. This compound is made using silver and phosphide (3-). The molecular weight of silver phosphide is 354.578 g/mol. The IUPAC name of the compound is trisilver, phosphorous(3). This compound is canonicalized with a count of 4 heavy atoms and 4 covalently-bonded units.
What is Copper Phosphide?
Copper phosphide is a product of copper and phosphorous that does not react with water. This compound is a phosphide of copper. The molecular formula of copper phosphide is CU3P. This compound is yellowish-grey in colour with a brittle crystalline structure, and when this compound is put under ultraviolet light, it is known to show fluorescence.
CU3P can be created photochemically with ultraviolet radiation. The process would involve irradiating cupric hypophosphite with ultraviolet radiation. It can also be created by a reaction of red phosphorous with a copper-rich compound inside a reverberatory furnace or inside a crucible. This compound is known for being a very good deoxidizer of copper.
What is Cadmium Phosphide?
The chemical formula of cadmium phosphide is Cd3P2. Cadmium phosphide is a chemical compound that is inorganic in nature. It has the appearance of white-bluish or grey, and it works as a semiconductor material with a 0.5 eV bandgap. This compound is used to produce pesticides, parts of laser diodes, and high-frequency and high-power electronic goods.
The reaction of cadmium and phosphorus creates this compound. There are no special environments required for the creation of this compound. This compound is of crystalline nature, and at room temperature, it is found in tetragonal form.
Cadmium phosphide is one of the main reasons for cadmium poisoning. This compound is hazardous to human health as it is very poisonous if swallowed. The reaction of gastric acids with this compound creates phosphine gas which is deadly for human beings. This compound is also carcinogenic in nature, making it more harmful to human beings.
What is Aluminium Phosphide?
Aluminium phosphide is an inorganic compound; the chemical formula of this compound is AlP. This compound is highly toxic to human beings and is used as a semiconductor material and a fumigant. This compound appears to be green-grey-yellow in colour and is present in powder form. Special care needs to be taken to ensure that this compound is not exposed to moisture when it is being prepared. Exposure to moisture would lead to the generation of phosphine gas which is highly toxic.
Al phosphide is used as pesticides, insecticide, and rodenticide; it is highly toxic and can even lead to ignition or explosion if phosphine gas is released. When sold, this pesticide is balanced with ammonia to reduce the possibility of combustion or explosion. Aluminium phosphide is available in the market through upl aluminium phosphide tablets that are used for the purpose of protecting cereal grain from pests, insects, and rodents.
There are different types of metal phosphide, most of which are highly toxic in nature and need judicious use with special precautions to ensure no accidental deaths due to the compound. Aluminium phosphide is often used in suicide cases; committing suicide by aluminium phosphide is common in India.
These are some of the examples of types of phosphides; there are more examples, such as lead phosphide and phosphide aluminium.
Solved Examples
Q1: What is the Value of the Phosphide Ion When Combined with Metal?
A) P3-
B) P4
C) P1
D) P2+
Answer: A) P3+
Q2: Ag3p is the Molecular Formula of Which Compound?
A) Aluminium Phosphide
B) Copper Phosphide
C) Silver Phosphide
D) Cadmium Phosphide
Answer: C) Silver Phosphide
Q3: Which Compound is Found in a Tetragonal Form at Room Temperature?
A) Silver Phosphide
B) Cadmium Phosphide
C) Aluminium Phosphide
D) Copper Phosphide
Answer: B) Cadmium Phosphide.
FAQs on Phosphide Chemistry Definition Structure and Reactions
1. What is a phosphide in chemistry?
A phosphide is a compound that contains the phosphide ion (P3−), in which phosphorus has a −3 oxidation state.
- Phosphides are typically formed when phosphorus reacts with metals.
- They are usually binary ionic or covalent compounds.
- Example: Na3P (sodium phosphide) contains three Na+ ions and one P3− ion.
2. What is the formula and charge of the phosphide ion?
The phosphide ion has the formula P3− and carries a −3 charge.
- Phosphorus gains three electrons to complete its octet.
- This gives it the same electron configuration as argon.
- The −3 charge is common when phosphorus reacts with metals.
3. How are metal phosphides formed?
Metal phosphides are formed by the direct reaction of a metal with phosphorus or by reduction of phosphate compounds.
- Direct synthesis example: 3Mg(s) + 2P(s) → Mg3P2(s)
- In this reaction, magnesium is oxidized to Mg2+ and phosphorus is reduced to P3−.
- The product Mg3P2 is magnesium phosphide.
4. What happens when a phosphide reacts with water?
When a phosphide reacts with water, it typically produces phosphine gas (PH3) and a metal hydroxide.
- Example: Mg3P2(s) + 6H2O(l) → 3Mg(OH)2(aq) + 2PH3(g)
- Phosphine (PH3) is a toxic, flammable gas.
- This reaction is a hydrolysis reaction.
5. What is the difference between a phosphide and a phosphate?
A phosphide contains phosphorus in the −3 oxidation state, while a phosphate contains phosphorus in the +5 oxidation state as PO43−.
- Phosphide example: Ca3P2
- Phosphate example: Ca3(PO4)2
- Phosphides are typically formed with metals under reducing conditions.
- Phosphates are common in biological systems and fertilizers.
6. What are some common examples of phosphides?
Common examples of phosphides include Na3P, Ca3P2, and AlP.
- Sodium phosphide (Na3P) – ionic compound with alkali metal.
- Calcium phosphide (Ca3P2) – alkaline earth metal phosphide.
- Aluminum phosphide (AlP) – used as a pesticide and fumigant.
7. What is aluminum phosphide used for?
Aluminum phosphide (AlP) is mainly used as a fumigant pesticide because it releases phosphine gas when exposed to moisture.
- Reaction: AlP(s) + 3H2O(l) → Al(OH)3(aq) + PH3(g)
- Phosphine gas kills insects and rodents in stored grains.
- It must be handled carefully due to its toxicity.
8. Are phosphides ionic or covalent compounds?
Phosphides can be ionic or covalent depending on the metal involved.
- Ionic phosphides form with highly electropositive metals like Na or Ca (e.g., Na3P).
- Covalent or interstitial phosphides form with transition metals (e.g., FeP).
- Bonding depends on electronegativity difference and metal character.
9. How do you write the formula of a metal phosphide?
To write the formula of a metal phosphide, balance the metal cation charge with the P3− anion charge.
- Step 1: Identify the metal ion and its charge (e.g., Ca2+).
- Step 2: Combine with P3−.
- Step 3: Balance charges: 3 × (+2) and 2 × (−3) → total 0.
- Result: Ca3P2.
10. Why are phosphides considered strong reducing agents?
Phosphides are strong reducing agents because phosphorus in P3− has a low oxidation state and readily loses electrons.
- Phosphorus can be oxidized from −3 to 0, +3, or +5.
- This tendency to lose electrons makes phosphides reactive with water and acids.
- Example: Reaction with acid produces PH3 gas and metal salts.
