10 Differences Between density and specific gravity

Difference Between Density and Specific Gravity

Difference Between Density and Specific Gravity

Have you ever wondered about the difference between density and specific gravity? These two concepts are often used in science and everyday life, but they have distinct meanings. In this article, we will explore what density and specific gravity are, examples of their applications, and how they differ from each other. Let’s dive in!

What is Density?

Density is a fundamental concept in physics and materials science. It refers to the amount of mass per unit volume of a substance. In simpler terms, density tells us how closely packed the particles of a substance are. The formula to calculate density is:

Density = Mass / Volume

Examples of Density

Here are a few examples that illustrate the concept of density:

  • Iron has a higher density than water, which is why it sinks in water.
  • A block of wood floats in water because its density is lower than that of water.
  • Helium gas has a very low density, which is why helium-filled balloons float in the air.

What is Specific Gravity?

Specific gravity is a ratio that compares the density of a substance to the density of a reference substance, usually water. It provides a way to measure the relative density of different materials. The formula to calculate specific gravity is:

Specific Gravity = Density of Substance / Density of Water (or other reference substance)

Examples of Specific Gravity

Here are a few examples of specific gravity in action:

  • Gold has a specific gravity of approximately 19.3, which means it is 19.3 times denser than water.
  • Ethanol has a specific gravity of about 0.79, indicating that it is less dense than water.
  • Ice has a specific gravity of 0.92, meaning it is slightly less dense than liquid water.

Differences Table

Difference Area Density Specific Gravity
Formula Density = Mass / Volume Specific Gravity = Density of Substance / Density of Water
Reference Substance No reference substance required Reference substance (usually water) is necessary
Unit of Measurement Kilograms per cubic meter (kg/m³) No unit (dimensionless)
Relative Comparison Indicates the absolute mass per unit volume Compares the density to that of a reference substance
Usage Widely used in calculations and scientific experiments Commonly used in industries like oil, brewing, and winemaking
Temperature Dependency Density changes with temperature Specific gravity remains constant regardless of temperature
Value Range Can take any positive value Usually between 0 and 2 for liquids and solids
Standard Units No standard unit No standard unit
Measurement Equipment Density meters, pycnometers, hydrometers Hydrometers, digital densimeters
International System of Units (SI) kg/m³ No standard SI unit


In summary, density and specific gravity are both important concepts related to the measurement of density. Density represents the absolute mass per unit volume, while specific gravity compares the density of a substance to that of a reference substance, typically water. They differ in their formulas, units of measurement, usage, and other characteristics. Understanding these differences can help in various scientific, industrial, and everyday applications.

People Also Ask:

1. What is the importance of density in everyday life?

Density is important in everyday life as it affects how objects interact with each other and their environment. For example, it determines whether an object sinks or floats in a liquid, the efficiency of packaging materials, and the insulation properties of materials.

2. How is density used in industry?

Density is used in various industries such as oil exploration (to determine the density of crude oil), winemaking (to measure sugar content in grapes), and brewing (to control the concentration of alcohol in beer).

3. Why is specific gravity important?

Specific gravity is important because it allows us to compare the density of different materials objectively. It is commonly used in industries to determine the concentration or purity of solutions, measure the density of fuels, and assess the quality of gemstones.

4. Is specific gravity affected by temperature?

No, specific gravity remains constant regardless of temperature. It is a dimensionless quantity and is dependent only on the relative densities of the substances being compared.

5. How is specific gravity measured?

Specific gravity can be measured using a variety of instruments such as hydrometers and digital densimeters. These devices compare the density of a substance to that of a reference substance, typically water, and provide a numerical value.

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