Mass Percent Formula

What is Mass per cent?

Mass per cent is a way of expressing a concentration or describing the component in a particular mixture. The solution composition can be described in mass percentage which shows the mass of solute present in a given mass of solution. The quantity of solute is expressed in mass or by moles. For a solution, the mass per cent is described as the grams of solute per grams of solution, multiplied by 100 to get the percentage.

Mass per cent Formula

The Mass per cent formula is expressed as solving for the molar mass also for the mass of each element in 1 mole of the compound. You can determine the mass percentage of each element with these masses.

\(\begin{array}{l}\text{Mass percentage} = \frac{\text{Mass of solute}}{\text{Mass of solution}}\times 100\%\end{array} \)

Example 1

An aqueous solution of sodium chloride (CaCl2) is prepared. Determine the mass of 5%(m/m) solution of calcium chloride that can be prepared using 100 g of calcium chloride.


The interpretation of mass/mass per cent number shows that 5g of CaCl2 is used to prepare 100g of solution.

g solution = (100g CaCl2 x 100g solution) / 5g CaCl2

g solution = 2 x 103 g solution

Hence, 2 x 103 g of 5% (m /m) solution can be prepared using 100g CaCl2

Example 2

Determine how many grams of sugar is present in 1.500g pf 1.50% solution of sugar in water.


Since mass percentage gives the mass of sugar in 100g of solution.

The two conversion factors can be solved as follows,

1.50g sugar / 100g solution are inverted to 100g solution / 1.50g sugar

the given solution by the first conversion

G sugar = (1.500g solution x 1.5g solution) / 100g solution

G sugar = 22.5g sugar

Hence, 22.5g sugar is present in 1.500g of 1.50% solution.


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