Question

Determine which of the following properties are intensive and which are extensive: (a) length, (b) volume, (c) temperature, (d) mass

Short answer

(a) Length - Extensive, (b) Volume - Extensive, (c) Temperature - Intensive, (d) Mass - Extensive.

Step-by-step solution

Understanding Intensive and Extensive Properties

First, let's define what intensive and extensive properties are. Intensive properties do not depend on the amount of matter present. Common examples include temperature, density, and color. Extensive properties depend on the amount of matter. Examples include mass, volume, and length.

Analyze Property (a) - Length

Length is an extensive property because it depends on the amount or size of the material present. If you combine two rods, the total length will be the sum of the individual lengths, showing dependency on the amount.

Analyze Property (b) - Volume

Volume is an extensive property since it changes with the quantity of the substance. If you have two liters of water and add another liter, the volume becomes three liters, which reflects the dependency on the amount.

Analyze Property (c) - Temperature

Temperature is an intensive property because it does not depend on the amount of substance present. Whether you have a liter of water or just a milliliter, the temperature can remain the same given the same conditions.

Analyze Property (d) - Mass

Mass is an extensive property as it depends on the amount of substance. More substance means more mass, showing its dependency on the quantity of matter.

Key concepts

Extensive Properties

Extensive properties are those which grow or shrink depending on the amount of matter in a sample. Simply put, these properties are linked to how much stuff you have. When you add or take away material, extensive properties change. For example, if you have a 500g block of cheese and add another 500g block, the total mass becomes 1000g. This demonstrates that mass is an extensive property because it changes with quantity. Similarly, length also falls under this category. If you take two equal lengths of rope, say each 5 meters, and join them, you now have a rope that’s 10 meters long. This illustrates how length is directly dependent on the amount of material and hence is extensive. Volume, another extensive property, behaves similarly. Pouring one liter of milk into a container and then adding another liter increases the total volume to two liters, making volume clearly dependent on the amount of substance.

Intensive Properties

Intensive properties are different from extensive properties. These do not change with the amount of substance present. No matter how much or how little of a substance you have, these properties stay the same. Temperature is an excellent example of an intensive property. Imagine you have one cup of coffee and a full pot, both at 90°C. Even though the amounts differ, the temperature remains constant in both cases as long as they are under the same conditions. Another common intensive property is density. Consider a block of gold; whether you have a tiny gold nugget or a giant gold bar, the density remains the same. Thus, intensive properties are specifically useful as they can characterize substances without depending on their quantity.

Physical Properties in Chemistry

Physical properties are attributes that can be observed or measured without changing the substance’s chemical identity. These are crucial in identifying and characterizing materials. Among these, properties are divided into two main categories: intensive and extensive. Physical properties are typically unique to each material and are quite useful in the fields of chemistry and materials science.

• Example: The melting point of ice is a physical property that can be observed without imparting any change to the chemical structure of water.
• Other Examples: Ductility, hardness, and conductivity also count as physical properties.

Understanding these properties help us get insights into the behavior of substances under different scenarios. For example, knowing the boiling point of a liquid can help in designing equipment for distillation processes.