What are the different ways of …

1. Concentration in Parts Per Million (ppm)

The parts of a component per million parts (10⁶) of the solution.

ppm(A)=Mass of ATotal mass of the solution×106

2. Mass Percentage (w/w):

When the concentration is expressed as the percent of one component in the solution by mass it is called mass percentage (w/w). Suppose we have a solution containing component A as the solute and B as the solvent, then its mass percentage is expressed as:

Mass % of A = Mass of component A in the solutionTotal mass of the solution×100

3. Volume Percentage (V/V):

Sometimes we express the concentration as a percent of one component in the solution by volume, it is then called as volume percentage and is given as:

volume % of A = Volume of component A in the solutionTotal volume of the solution×100

For example, if a solution of NaCl in water is said to be 10 % by volume that means a 100 ml solution will contain 10 ml NaCl.

4. Mass by Volume Percentage (w/V):

This unit is majorly used in the pharmaceutical industry. It is defined as the mass of a solute dissolved per 100mL of the solution.

5. Molarity (M):

One of the most commonly used methods for expressing the concentrations is molarity. It is the number of moles of solute dissolved in one litre of a solution. Suppose a solution of ethanol is marked 0.25 M, this means that in one litre of the given solution 0.25 moles of ethanol is dissolved.

6. Molality (m):

Molality represents the concentration regarding moles of solute and the mass of solvent. It is given by moles of solute dissolved per kg of the solvent. The molality formula is as given-

Molality(m)=Moles of solute / Mass of solvent in kg

7. Normality

It is the number of gram equivalents of solute present in one liter of the solution and it is denoted by N.

N=Weight of solute in gramsEquivalent mass×Volume in liter

The relation between normality and molarity.

• N x Eq.Wt = Molarity x Molar mass
• N = Molarity x Valency
• N = Molarity x Number of H⁺ or OH^– ion