Question

a. Define physical property. b. List two examples of physical properties.

Short answer

A physical property is a characteristic that can be observed without changing the substance's identity. Examples include density and color.

Step-by-step solution

Define a Physical Property

A physical property is a characteristic of a substance that can be observed or measured without changing the substance's chemical identity. Examples include density, color, mass, volume, and state of matter (solid, liquid, gas).

Example 1 - Density

Density is a physical property that measures the amount of mass per unit volume of a substance. It is usually expressed in grams per cubic centimeter (g/cm³).

Example 2 - Color

Color is a physical property that describes the appearance of a substance as perceived by the human eye. It can identify substances and can also be an indication of purity or the presence of some impurities.

Key concepts

Characteristics of Substances

When studying physical properties, we're essentially examining the characteristics of substances. These are traits that can be observed or measured without altering the substance itself. This means the substance's chemical identity stays the same. The major characteristics include:

• Density
• Color
• Mass
• Volume
• State of matter (solid, liquid, gas)

Understanding these traits helps in identifying and differentiating between substances. It’s like recognizing people by their height, weight, or hair color. These attributes don’t change who they are fundamentally.

Density

Density is a crucial physical property. It tells us how much mass is packed into a given volume. The formula to calculate density is: \[\text{Density} = \frac{\text{Mass}}{\text{Volume}}\] This property is often measured in grams per cubic centimeter (g/cm³). For instance, if you have a substance with a mass of 10 grams and a volume of 2 cubic centimeters, its density would be: \[\text{Density} = \frac{10 \text{ g}}{2 \text{ cm}^3} = 5 \text{ g/cm}^3\] More compact substances have higher densities. For example, metals tend to have higher densities than liquids like water. Understanding density is important in fields like material science, chemistry, and physics.

Color

Color is another fundamental physical property. It describes how a substance interacts with light and is perceived by our eyes. Color can help identify substances and sometimes indicates their purity. Think about a gold nugget—it has a distinct golden-yellow color. However, if impurities are present, the color might differ. This makes color useful in fields like chemistry and mineralogy. It’s an easy-to-use property that often gives quick information about a substance without requiring complex equipment.