Question

The following data refer to the element phosphorus. Classify each as a physical or a chemical property (a) It exists in several forms, for example, white, black, and red phosphorus. (b) It is a solid at \(25^{\circ} \mathrm{C}\) and \(1 \mathrm{~atm}\). (c) It is insoluble in water. (d) It burns in chlorine to form phosphorus trichloride.

Short answer

Question: Classify each of the following properties of phosphorus as either a physical or chemical property: (a) Phosphorus exists in several forms, such as white, black, and red phosphorus. (b) Phosphorus is solid at \(25^{\circ} \mathrm{C}\) and \(1 \mathrm{~atm}\). (c) Phosphorus is insoluble in water. (d) Phosphorus burns in chlorine to form phosphorus trichloride. Answer: (a) Physical property (b) Physical property (c) Physical property (d) Chemical property

Step-by-step solution

(a) Classification of phosphorus existence in several forms

The property mentions the existence of phosphorus in several forms, such as white, black, and red phosphorus. These forms refer to the different physical appearances of phosphorus, which can be observed without altering its chemical identity. Thus, this is a physical property.

(b) Classification of phosphorus being solid at \(25^{\circ} \mathrm{C}\) and \(1 \mathrm{~atm}\)

The property states that phosphorus is a solid at a specific temperature and pressure. This information describes the physical state of phosphorus under certain conditions, which can be observed or measured without changing the chemical identity of the substance. Therefore, this is a physical property.

(c) Classification of phosphorus being insoluble in water

The property describes that phosphorus cannot dissolve or mix with water. Solubility is a property that can be observed without changing the chemical identity of the substance. Thus, this property is classified as a physical property.

(d) Classification of phosphorus burning in chlorine to form phosphorus trichloride

The property states that phosphorus reacts with chlorine to form a new compound, phosphorus trichloride. Since the reaction involves a change in the chemical identity of phosphorus, it is describing its ability to undergo a chemical change. Therefore, this is a chemical property.

Key concepts

Physical and Chemical Properties of Phosphorus

Phosphorus is a fascinating element with distinct physical and chemical properties that are essential to understanding its behavior in different contexts.

Physically, phosphorus appears as a solid at room temperature, specifically at 25 degrees Celsius and 1 atmosphere of pressure. Its insolubility in water is another physical property, which indicates that it cannot dissolve or mix with water. These traits are observed without altering the substance's identity.

Chemically, phosphorus is known for its vigorous reactions with other elements. For example, when it burns in chlorine, it transforms into phosphorus trichloride, which signifies a change in its chemical identity due to a reaction. Such chemical properties demonstrate the potential of phosphorus to engage in the formation of new compounds.

Allotropes of Phosphorus

Allotropes are different forms of the same element, with atoms arranged in distinct patterns resulting in unique properties. Phosphorus is well-known for exhibiting this phenomenon.

White Phosphorus

White phosphorus consists of P4 tetrahedra and is highly reactive due to the strain in its molecular structure. It is usually stored under water to prevent it from reacting with oxygen in the air.

Red Phosphorus

This allotrope is more stable and safer to handle than white phosphorus. Found often on the striking surfaces of matchboxes, red phosphorus can convert to white phosphorus when heated under the right conditions.

Black Phosphorus

The most stable allotrope, black phosphorus, has a layered structure, which gives it unique electrical and mechanical properties used in various applications like semiconductor technologies.

Phosphorus Trichloride

Phosphorus trichloride (P_{3}Cl_{3}) is an important chemical compound of phosphorus and chlorine. It's a colorless, fuming liquid with a pungent odor, used predominantly in the synthesis of other organophosphorus compounds. From the perspective of its formation, it serves as a direct example of phosphorus's reactivity, particularly its chemical properties.

The production of phosphorus trichloride involves a chemical reaction where the element burns in chlorine gas. This interaction demonstrates the element's affinity for chlorine and ability to form covalent halides. The process and resultant compound are integral to numerous industrial processes, including the manufacturing of pesticides and flame retardants.