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How do you find volume from specific weight?

Published in Volume Calculation 3 mins read

To find volume from specific weight, we first need to understand that "specific weight" is often used interchangeably with specific gravity. The provided reference clarifies that specific gravity is the ratio of the density of a substance to the density of a reference substance, making it unitless. However, water is frequently used as the reference substance. Let's clarify the method to calculate the volume by rephrasing the question as, How do you find volume from specific gravity when given the weight of a substance?

Here's how to calculate the volume:

Calculating Volume Using Specific Gravity and Weight

The key formula derived from the provided reference is:

  • Volume = (1 ml/g) x Weight (in grams) / Specific Gravity

Here's a breakdown of the steps:

  1. Understand Specific Gravity (S.G.): Specific gravity is a ratio. It is how many times more or less dense a substance is compared to the density of water.

    • If the S.G. is greater than 1, the substance is denser than water.
    • If the S.G. is less than 1, the substance is less dense than water.
    • For example, the S.G. of mercury is about 13.6, meaning it is 13.6 times denser than water.

  2. Convert Weight to Grams: Make sure the weight of the substance is in grams. If it’s in other units, convert it.

  3. Apply the Formula: Use the formula shown above, which assumes water as the reference substance with a density of 1 g/ml.

Example:

Let's say you have 100 grams of a substance with a specific gravity of 2.

  • Weight of the substance = 100 grams
  • Specific gravity (S.G.) = 2

Using the formula:

  • Volume = (1 ml/g) x 100 grams / 2
  • Volume = 50 ml

Therefore, the volume of the substance is 50 ml.

Important Considerations:

  • Reference Substance: Remember that this method assumes water is the reference substance for specific gravity, a common assumption.

  • Unit Consistency: Ensure all units are consistent (grams for weight, ml for volume).

  • Alternative Method using Density: If the density of the substance is known directly instead of specific gravity, you can find the volume using:

  • Volume = Mass/Density. Make sure your units are consistent to get the volume in a desired unit (e.g. grams and grams/ml will result in ml).

Summary Table:

Input Formula Output
Weight (grams), S.G Volume = (1 ml/g) x Weight (grams) / S.G Volume (ml)
Mass (grams), Density (g/ml) Volume = Mass (grams) / Density (g/ml) Volume (ml)

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