One technique to describe the concentration of an element in a compound or a component in a mixture is to use mass percentage. The mass of a component is divided by the total mass of the combination and multiplied by 100 percent to get the mass percentage.
Also known as: mass percent, (w/w) percent, (w/w) percent, (w/w) percent, (w/w) percent,
How to find mass mass percent US
Formula for Mass Percentage
The mass of the element or solute divided by the mass of the compound or solute equals the mass percent. To get a percent, multiply the value by 100.
The amount of an element in a compound is calculated using the formula:
(mass of element in 1 mole of compound / mass of 1 mole of compound) times 100 Equals mass percent
A solution’s formula is as follows:
(grammes of solute / grammes of solute plus solvent) times 100 Equals mass percent
or
(grammes of solute / grammes of solution) times 100 Equals mass percent
The final result is expressed as a percentage.
Example of a Mass Percentage
Example 1: Ordinary bleach contains 5.25 percent NaOCl by mass, or 5.25 g NaOCl per 100 g bleach.
Find the mass percentage of 6 g sodium hydroxide dissolved in 50 g water in Example 2. (Note: because water has a density of approximately 1, this type of inquiry is frequently answered in millilitres.)
To begin, calculate the total mass of the solution:
6 g sodium hydroxide + 50 g water Equals total mass
56 g total mass
The mass percentage of sodium hydroxide can now be calculated using the formula:
(6 g NaOH / 56 g solution) x 100 mass percent = (0.1074) x 100 answer = 10.74 percent mass percent = (grammes of solute / grammes of solution) x 100 mass percent = (grammes of solute / grammes of solution) x 100 mass percent = (grammes of solute / grammes of solution) x 100 mass percent = (grammes of solute / grammes of solution) x 100 mass percent = (grammes of NaOH
Example 3: Calculate the amounts of sodium chloride and water needed to make 175 g of a 15% solution.
This issue is a little odd in that it provides you the mass % and then asks you to figure out how much solute and solvent you’ll need to get to 175 grammes total mass. Begin by filling in the blanks in the following equation:
(grammes solute / grammes solution) times 100 Equals mass percent
(x grammes sodium chloride / 175 g total) times 100 = 15%
The amount of NaCl can be calculated by solving for x:
x = 15 x 175 / 100 x = 26.25 grammes sodium chloride
You now know how much salt you’ll need. The total amount of salt and water makes up the solution. Simply subtract the quantity of salt from the solution to get the needed mass of water:
water mass = total mass – mass of salt = 175 g – 26.25 g amount of water
Water mass = 147.75 g
Example 4: What is the hydrogen mass percent in water?
To begin, you’ll need the water formula, which is H2O. Then, using a periodic table, find the mass of 1 mole of hydrogen and oxygen (atomic masses).
1.008 grammes of hydrogen per mole
16.00 grammes of oxygen per mole
The mass percentage formula is then applied. The key to accurately conducting the computation is to remember that each water molecule contains two hydrogen atoms. So there are 2 x 1.008 grammes of hydrogen in 1 mole of water. The mass of the two hydrogen atoms and one oxygen atom add up to the total mass of the complex.
× 100 mass percent hydrogen = [(2 x 1.008) / (2 x 1.008 + 16.00)] mass percent = (mass of element in 1 mole of compound / mass of 1 mole of compound) x 100 mass percent hydrogen = [(2 x 1.008) / (2 x 1.008 + 16.00)] x 100% hydrogen = (2.016 / 18.016) x 100% hydrogen = 11.19 percent
