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Mass Percent Formula

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Mass Percent in chemistry is a unit of concentration, i.e. it tells us about the concentration of solute and solvent in the solution. The mass of a solute and solvent is used to determine the mass percent of the solution. In general, the mass percent is calculated using the formula mass of components divided by the mass of the total substance, and the result is multiplied by 100. In this article, we will learn about, Mass Percent, Mass Percent Formula, Examples, How to Find the Mass Percentage, Calculate the Percent by Mass, and others in detail.

What is Mass Percent?

A mass percent is a way of expressing the concentration of different components in a solution. The concentration of any solution in chemistry is easily described using the mass percent. The mass of the solute and the mass solvent are used to find the mass percent of the given solution. The mass percent of a solution is calculated by multiplying the grams of solute per gram of solution by 100. Suppose we are given a 10% Brine solution in 140 grams of solution. This explains that 14 grams of NaCl is present in 140 brine solution.

Mass Percent Formula

The Mass Percent of any substance is calculated using the formula added below,

Mass Percent = (Mass of components / Total mass) × 100%

Mass Percent = (Mass of solute / Mass of solution) × 100%

Mass is commonly represented in grams, but if the mass of solute and solvent is given in any unit (until both are in the same units) we can easily find the mass percent. “Mass Percent” is sometimes also known as “weight percent” or w/w%.

How to Find Mass Percentage?

To find the mass percentage we use the following steps added below,

Step 1: Note the mass of all the components of the given solution.

Step 2: Find the mass of the solute and solution individually by taking the sum of the mass of all the solutes in the solution.

Step 3: Use the Mass percent formula, to find the mass percent of the solution. The mass percent formula is,

Mass Percent = (Mass of Solute)/(Mass of Solution)×100 %

Step 4: Simplify and use the % symbol in the final answer to get the required mass percentage.

Thus, these steps are used to find the mass percentage of the of the given solution.

Calculate the Mass Percentage

We have learnt steps of how to find the mass percentage, let’s understand how calculate the mass percentage of a component using the steps mentioned above.

Example: Calculate the Mass Percent of 10g of solute dissolved in 90 g of water.


Given that, Mass of solute dissolved = 10 g

Mass of Solvent which is water here = 90g

Mass of Solution of 90 + 10 = 100 g

Hence, Mass Percent of Solute = (Mass of Solute/Mass of Solution) × 100 = (10/100)×100 = 10

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Examples for Mass Percent Formula

Example 1: Calculate the mass of a 5 percent (m/m) calcium chloride solution that is made with 100 g of calcium chloride.



  • Mass Percent = 5%
  • Weight of Solute (CaCl2) = 100 g

Let the weight of solution be x g

Now using the mass percent formula,

5 = (100/x) × 100

x = 10000/2 = 2000 grams

Thus, the weight of solution is 2 × 103 g solution

Example 2: In 367g of water, 7g of chlorine is dissolved. What is the chlorine content in water in terms of mass?



  • Mass of solute = 7 g (chlorine)
  • Mass of Solvent = 367 g (water)

Mass of solution = Mass of solute + Mass of Solvent

Mass of solution = 8 + 367

Mass of solution = 375 g


Mass Percent = (Mass of solute / Mass of solution) × 100%

∴ Mass Percent = (7 / 375) × 100%

∴ Mass Percent = 1.866%

Example 3: Calculate the amount of cane sugar required to make 284 g of a 30% sugar solution.



  • Mass Percentage = 30%
  • Mass of solution = 284 g


Mass Percent = (Mass of solute / Mass of solution) × 100%

∴ 30 = (Mass of solute / 284) × 100%

∴ Mass of solute = (30*284)/100

∴ Mass of solute = 85.2 g

Example 4: With 500 gm of water and 3.12% mass by mass solute combined together, a solution is created. Calculate the solute’s mass.



  • Mass of Solvent = 500 g
  • Mass by Mass percentage =3.12 %

Let the mass of solute is x g

Mass of Solution = ( x+ 500)


Mass Percent = (Mass of solute / Mass of solution) × 100%

∴ Mass of solute = (Mass percentage × mass of solution) / 100

∴ Mass of solute = (3.12 × (x+500)) / 100

∴ 3.12x +1560 = 100x

∴ 3.12x – 100x = -1560

∴ x = 16.10 g

∴ Mass of solute = 16.10 g

Practice Questions on Mass Percent Formula

Q1: A solution of 300 g contain MgCl2 worth 25 g. Find the Mass Percent of Magnesium Chloride

Q2: With 350 ml density as solvent a compound X weighing 30 g is dissolved. Find the Mass Percent of Compound X. Given that density of alcohol is 789 kg/m3

Q3: A solution contain 23% of a solute (m/m). The mass of the solution is 230g. Find the mass of the solute dissolved.

Q4: Calculate the Percent by Mass when 20g of CaCl2 is dissolved in 180 g of solvent.

Q5: Calculate the Percent by Mass when 35 g of CCl4 is dissolved in 140g of solvent.

Mass Percent Formula – FAQs

1. What is Mass Percentage and its Formula?

Mass percentage or Mass Percent is a way of measuring concentration of any solution. It is calculated using the formula, Mass Percent = (mass of chemical / total mass of compound) x 100.

2. Why is Mass Percentage Important?

Mass Percentage/Mass Percent is used easily explain the concentration of any solution.

3. What is the SI unit of Mass?

The SI unit of mass is Kilogram.

4. How do you Calculate Mass Percent?

Mass percent of an object is calculated by taking the ratio of mass of object to the mass of solution and then multiplying the result with 100.

5. How to Find Mass the Percentage from Total Mass?

If the total mass of the substance is given the we first find the mass of the solute by using the formula mass of solution is the sum of mass of solute plus mass of solvent. Then we use the mass percent formula to calculate the mass percent.

6. How to Calculate the Percent by Mass?

To Calculate the percent by Mass divide the mass of given substance by total mass of the component in which the substance is present and multiply it by 100

Last Updated : 19 Dec, 2023
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