Mass Percentage: Class 12 Chemistry Notes, Definition, Formulas & Examples

The mass percent of a component in the mixture is calculated using the formula:

$\mathrm{Mass percent}=\frac{\mathrm{Mass} \mathrm{of} \mathrm{the} \mathrm{component}}{\mathrm{Total} \mathrm{mass} \mathrm{of} \mathrm{the} \mathrm{mixture}}\times 100\%$

Problem: 10 grams of salt dissolved in 90 grams of water. What is the mass percent of salt?

Answer: We have

the mass of the component, which is 10 g, and

The total mass of the mixture is 10gm + 90gm

to find the mass per cent of a salt, we use the formulas

$\mathrm{Mass percent of salt}=\frac{10}{10+90}\times 100\%$

= $\frac{10 g}{100 g}\times 100\%$

= 10%

The solution contains 10% salt by mass.

• Define the equation for mass per cent of a compound.
• The formula for mass per cent of a compound is $\mathrm{Mass percent}=\frac{\mathrm{Mass} \mathrm{of} \mathrm{the} \mathrm{component}}{\mathrm{Total} \mathrm{mass} \mathrm{of} \mathrm{the} \mathrm{mixture}}\times 100\%$ . 
• Find the total mass of the compound. This may be the denominator within the mass percent calculation.
• Identify the mass of the given chemical. This mass is the numerator within the mass percent calculation.
• Substitute the values for variables into the mass percent equation.
• Determine the mass percent. Divide the mass of the chemical by the entire mass of the compound and multiply by 100. This gives you the mass percent of the chemical.