[Physics Class Notes] on Difference Between Density and Specific Gravity Pdf for Exam

The expression of density in proportion to the density of a standard or reference is used to calculate specific gravity. Water is usually used as a benchmark. Density, on the other hand, is measured in weight units relative to size. It’s worth noting that specific gravity is a one-dimensional number with no dimensions. The ratio of mass to volume is used to calculate density, which is a specific attribute of matter. Specific gravity, often known as relative density, is the measurement of density in comparison to the density of pure water.

What is the Definition of Density?

Density is a feature of matter that may alternatively be defined as the ratio of mass to a unit volume of the substance. It is usually expressed in grams per cubic centimetre or kilogramme per cubic metre units. The mass per unit volume is used to calculate it. As a result, density is a measurement of how compact a material or object is. It is a scalar quantity since it lacks direction. Its measurement is a method of determining mass in a continuous system.

What is the Definition of Specific Gravity?

It is the measurement of density in comparison to the density of a set of standard reference materials. In most cases, the reference material is pure water. A substance with a specific gravity of less than one can also float on water. The specific gravity of a substance can be calculated using a simple ratio of the substance’s density to the density of a standard substance.

The density of a substance or liquid in comparison to the density of water at a certain temperature and pressure is known as specific gravity. As a result, any change in temperature or pressure will have an impact on the density.

In everyday life, specific gravity values of a substance are uncommon. It is, nevertheless, extremely useful in forecasting whether or not anything would float in water. It can also be used to determine whether one substance is denser than another. Pure water has a density of about 1 gramme per cubic centimetre. As a result, specific gravity and density are nearly equal. Density is, in fact, only slightly less than the specific gravity number.

Because density has units and specific gravity is dimensionless, the two are never the same, but they are numerically equal when three conditions are met:

1. Density is measured in grammes per cubic centimetre, grammes per millilitre, or kilogrammes per litre;

2. Density and Specific Gravity are measured at the same temperature; and

3. The Specific Gravity is referenced to water at 4 degrees Celsius, where its Density is very close to 1 gramme per cubic centimetre. Multiplying the Specific Gravity by the Density of water at the reference temperature yields the density of a material.

Specific Gravity is also expressed on a variety of arbitrary scales. The Baumé scale, created in 1800 by a French chemist named Antoine Baumé, is one of them. It involves two formulas, one for Specific Gravities less than one and the other for Specific Gravities more than one, and is used to express the Specific Gravity of liquids. These are the two formulas:

[text{degrees Baume} (^{o}Be) = frac{140}{text{Sp.Gr.at} 60^{o}F/60^{o}F} -130(text{Sp. Gr}.<1)] 

[text{degrees Baume} (^{o}Be) = 145- frac{145}{text{Sp.Gr.at} 60^{o}F/60^{o}F} (text{Sp. Gr}.>1)]  

How to Calculate Density and Specific Gravity

Except for predicting whether or not something will float on water and comparing whether one substance is more or less dense than another, specific gravity numbers aren’t very useful. However, because the density of pure water is so close to 1 (0.9976 grammes per cubic centimetre), specific gravity and density are almost identical when expressed in g/cc. Specific gravity is somewhat less dense than density.

Things to keep in Mind

1. Density is only slightly less than specific gravity in terms of number.

2. The density of pure water is approximately 1 gram per cubic centimetre.

3. A single material’s specific gravity cannot be estimated.

4. Specific gravity varies with reference, but density remains constant.

5. When we give a substance external temperature, we can vary its density.