All About Normality and Molarity

Solutions and different ways to calculate them

According to chemistry, a homogeneous combination of at least two substances in relative sums can be differed constantly up to what is known as the restriction of solvency. The term solution is ordinarily applied to the fluid condition of the issue, yet arrangements of gasses and solids are conceivable. The substance wherein a solute breaks down to create a homogeneous blend is called a solvent, and the substance that dissolves in a solvent to produce a homogeneous mixture is called a solute. 

Solute exists in liquid, solid as well as in the gaseous state. There can be a homogenous mixture in which the solutes are spread equally in the solution and hence maintain uniformity in the mixture. Also, they can be heterogeneous in that more than one type of solute is mixed, and therefore no uniformity is present in the mixture as the spreading of the solute is uneven. The ability of a solute to dissolve in a solvent is known as the solubility of the solvent. 

The solvent in the solution contributes to most of the volume that can be seen in a solution. How much solute a solvent can dissolve is decided by the temperature of the medium. In a homogenous mixture, we know that the amount of solvent is uniformly present, so this means that per volume, the amount of solute is equal. To maintain a thermodynamic equilibrium, several solvent particles surround the solute particle. Polarity plays an important role as well. Solvents are usually divided into two categories depending on their polarity, i.e., polar (example water) and non-polar (example hydrocarbons) solvents. The boiling point is always lower for the solvent in comparison to the solute. 

For example, you all must be aware that salt can easily dissolve in water, so here, salt is the solute, and water is the solvent. Another example could be different protons that can be found in the cytosol of an animal cell. Here the protons are the solutes that are dissolved in the cytosol. 

A simple calculation to find the concentration of a solution when all the substances are in their standard units can be done with the following formula:

Just find out the total volume by using a measuring cylinder and then use the formula:

                                   C= m/V

Where C is the concentration, m is the mass of solute, and V is the total volume of the solution. 

But when there are more complex solutions, then we need to measure the liquids based on volume instead of mass. 

Two of these ways are:

• Molarity
• Normality

1. Molarity (M)

Molarity demonstrates the number of moles of solute per litre of arrangement (moles/Litre) and is perhaps the most well-known unit used to quantify the grouping of an answer. This method can be utilised to compute the volume of dissolvable or how much solute. The connection between two arrangements with a similar measure of moles of solute can be addressed by the formula c1V1 = c2V2, where c is focus and V is volume. SI unit for molar concentration is mol/m3.

The formula for molarity is :

Molarity (M)=no. of moles of a solute / volume of solution

Let us see an example to calculate molarity:

Q.1 What is the molarity of a solution with 50 grams of NaCl in 3 L of solution?

Answer:

Here we are given that, 

NaCl concentration- 50 grams               

The molecular weight of NaCl is -58.4 grams

First, we need to calculate the number of mole of NaCl

50 g of NaCl * (1/58.4) = 0.8 moles of NaCl

Now we are also given that the total volume of the solution is 3L

So,               M=n/V

M= 0.8/3,     M = 0.28 Molar

2. Normality

It is a proportion of fixation equivalent to the gram equivalent weight per litre of solution. Gram equivalent weight is the proportion of the reactive limit of a particle. The solute’s job in the response is to decide the arrangement’s normality. 

N = molar concentration/equivalence factor

or

N = gram equivalent weight/liters of solution

or

N = M* No. of equivalents

Units of normality are expressed as eq/L or meq/L

Let us go through an example:

1. For acids such as a 1 M H2SO4 solution, the normality (N) of this solution will be 2 N as 2 moles of H+ particles are available per litre of solution.
2. Another example we can take is :

Find the normality of 0.2 M H2SO4 (sulfuric corrosive) for the response:

H2SO4 + 2 NaOH → Na2SO4 + 2 H2O

As indicated by the situation, 2 moles of H+ particles (2 counterparts) from sulfuric corrosives respond with sodium hydroxide (NaOH) to shape sodium sulfate (Na2SO4) and water. Analysing the condition:

N = molarity x reciprocals

N = 0.2 x 2

N = 0.4 Normal

Conclusion

In research labs, you can see these quantities being used very frequently as the mixing of different reagents keeps on being in use. These are very important to be understood as they are important to calculate the concentration of the solution. Molarity and normality are two very different ways but are related to each other. Hope this article gives you a little clarity on these concepts.