Alligation calculator

Calculate alligation ratio of solutions of two different concentrations to prepare intermediate concentration. You can also add volumes or parts of any concentrations to know the parts of third concentration.

What is Alligation?

Alligation is a simple technique of mixing two solutions of different concentrations to produce an intermediate concentration. It is somewhat different from dilution where normally we use solvent or water to decrease the concentration.

Suppose you have a 20N concentrated solution of a substance. How can you convert it into 10N? Simply, by dilution. You can use event the following formula

N₁V₁ = N₂V₂

Substituting in the equation,

20 * V₁ =10 *V₂        or      V₁/ V₂ =0.5

So we have to dilute the solution to half of its concentration. That’s so simple.

Now consider another situation. You have two solutions of a same substance at different concentrations 20N and 10N. Now you want 15N solution by using these two solutions. Here allegation comes in to the play.

Simply you can apply alligation method and can find the ratio by which two solutions to be mixed. Here in order to get 15N solution 1 part of 20N solution is to be mixed with 1 part of 10N solution.

How to use this calculator?

You can do the allegation calculation very easily with a single click with this calculator. Enter the values for higher concentration, lower concentration and required intermediate concentration.  Simply click to get the allegation ratio.

You can also add the volume/part of one of the concentration to get the volume/parts of other solutions to be mixed. Click on the add volumes.

Just enter volume/parts of any one solution you want to use and get the volumes/parts of other solutions automatically by a click.

Practical examples

Here let’s see few examples of allegation calculations and how can we use this calculator.

How can you make 10% solution from two solutions of 18% and 6% ?

Solution:   Let’s identify the data. Higher concentration is 18%, lower concentration is 6% and required concentration is 10%. So placing these values in the calculator, the allegation ratio will be 1:3.

So 1 part of the 18% solution is to be mixed with 3 parts of 10% solution to get finally 4 parts of 6% solution.

Example 2

How many ml of two solutions of 1.3M and 0.3M are to be mixed to get 100 ml of 0.6M solution?

Solution:   Again here higher concentration is 1.3M, lower concentration is 0.3M and required concentration is 0.6M. In this example, we need to calculate volumes of each solution to be mixed to get a final solution of 100 ml. So let’s first fill the values of three concentrations in the calculator. Then click on add volume. Select “Parts of Reqd conc” and “ml” as the unit. Then put 100 ml as the value in the field and Click to calculate.

So 30 ml of higher concentration 1.3M should be mixed with 70 ml of lower concentration 0.3M to produce 100 ml of final required concentration 0.6M.