Question

Label each of the properties of iodine as intensive (I) or extensive \((\mathrm{E})\). (a) Its density is \(4.93 \mathrm{~g} / \mathrm{mL}\). (b) It is purple. (c) It melts at \(114^{\circ} \mathrm{C}\). (d) One hundred grams of melted iodine has a volume of \(122 \mathrm{~mL}\) (e) Some iodine crystals are large.

Short answer

Question: Label the following properties of iodine as either intensive (I) or extensive (E): (a) Density: \(4.93 \mathrm{~g} / \mathrm{mL}\) (b) Color: purple (c) Melting point: \(114^{\circ} \mathrm{C}\) (d) Volume of one hundred grams of melted iodine: \(122 \mathrm{~mL}\) (e) Size of iodine crystals: large Answer: (a) Intensive (I) (b) Intensive (I) (c) Intensive (I) (d) Extensive (E) (e) Extensive (E)

Step-by-step solution

Property (a)

The density of iodine is given as \(4.93 \mathrm{~g} / \mathrm{mL}\). Density is defined as mass per unit volume, which means it doesn't depend on the amount of the substance. Therefore, the density is an intensive property (I).

Property (b)

The color of iodine is stated as "purple". Color is a property that doesn't rely on the amount of a substance. Thus, the color is an intensive property (I).

Property (c)

The melting point of iodine is given as \(114^{\circ} \mathrm{C}\). The melting point of a substance, like other phase transitions, is independent of the amount of the substance. Therefore, the melting point is an intensive property (I).

Property (d)

The volume of one hundred grams of melted iodine is given as \(122 \mathrm{~mL}\). Since this property refers specifically to the volume of a certain mass of iodine, it depends on the amount of substance. Therefore, this property is extensive (E).

Property (e)

The size of iodine crystals being large refers to the dimensions of the crystals. Size or volume of a substance will change depending on the amount of the substance. Therefore, the size of iodine crystals is an extensive property (E). In summary: (a) Intensive (I) (b) Intensive (I) (c) Intensive (I) (d) Extensive (E) (e) Extensive (E)

Key concepts

Chemical Properties

Chemical properties of a substance include its reactivity with other chemicals, the types of chemical bonds it forms, its flammability, and other attributes that pertain to its composition and reactions. These properties are essential in identifying a substance and understanding its behavior in chemical reactions. For example, the reactivity of iodine with other elements or compounds contributes to its chemical properties and influences how it is used in various applications like medicine and photography.

Chemical properties are intensive because they are inherent to the substance and do not change with the amount of the material. Knowing the chemical properties helps predict how a substance will interact with others, which is crucial for safe handling and practical application in various industries.

Density of Substance

Density is a physical property that describes how much mass is contained in a specified volume of a substance, typically expressed as grams per milliliter (g/mL) or kilograms per cubic meter (kg/m^3). It's a key factor in determining whether a substance will float or sink when placed in a fluid. Because density is a ratio of mass to volume, it is not affected by the size or amount of the substance, making it an intensive property.

For example, iodine's density of 4.93 g/mL stays constant whether you have a tiny crystal or a large block. This property is crucial for understanding the behavior of materials under varying conditions and for identifying substances.

Melting Point

The melting point of a substance is the temperature at which it changes from a solid state to a liquid state. This physical property is characteristic of pure substances and is intensive, meaning it does not depend on the quantity of the material. The melting point can provide valuable information about the purity of a substance; impurities can alter the melting point, which is a principle used in techniques such as melting point determination in chemistry labs.

In our exercise, iodine's melting point is recorded at 114°C. This is a constant value for pure iodine, irrespective of whether we have a gram or kilogram of the substance, demonstrating its intensive nature.

Physical Properties

Physical properties are characteristics of a substance that can be observed or measured without changing its composition. These properties include but are not limited to color, phase (solid, liquid, gas), melting point, boiling point, density, and electrical conductivity. They are used to observe and describe matter.

Some physical properties, like melting point and density, are intensive and do not depend on the amount of substance. Others, such as volume and mass, are extensive and change with the quantity of material. For example, the color of iodine being purple is an intensive property – it will be the same regardless of the sample size. However, the volume, which is how much space the sample occupies, is extensive and will vary with the amount of iodine.