Concentrated and Diluted Solution

Concentration, according to the Oxford Dictionary, refers to “a close gathering of people or things”. Concentration in chemistry has a similar meaning. It basically answers the question, “how much is dissolved”, in “what amount of solution”.

A solution has two components- solute and solvent. The component which is present in the majority and dissolves the other component in it is called the solvent. On the other hand, the component present in the minority and dissolves in the other component is called the solute.  The amount of solute dissolved in the solvent is referred to as the concentration of the solution. 

A solution can be dilute or concentrated depending upon the concentration of the solution.  A concentrated solution has a high amount of solute dissolved in it whereas a dilute solution has a low amount of solute dissolved in it. 

Concentration

To understand concentration, let’s take the example of tetra packs of juices. Many of them display the information about the concentration of various ingredients in a given amount or a particular pack of the item. 25 percent concentration of mango pulp effectively means that mango pulp constitutes around 25 percent of the total amount of solution.

Taking a different approach, if we prepare around 100 grams of sugar solution using 20 grams of sugar, then the total concentration of sugar in the solution would be 20 per cent.  If the amount of sugar is increased to 50 grams, then the percentage of concentration would climb up to 50 per cent.

In a broad sense, the concentration of a solution refers to the total amount of solute dissolved in the given amount of solution. There are several methods to determine the concentration of a solution. Some of these are as follows:

1. Molarity-moles of solute/litres of solution
2. Mass Concentration(Mass by Volume)- Mass of solute/volume of solution
3. Volume Concentration(Volume by Volume)- Volume of solute/volume of solution
4. Number Concentration(Number of particles by volume)- Number of particles(atoms or molecules) of the solute/ total volume of solution
5. Mass Percent-(Mass of solute/Mass of solution)*100
6. Volume Percent-Volume of solute/Volume o solution*100

All these methods are essentially just different ways to determine the amount of the minority component (solute) dissolved (mixed) in the majority component (solvent) of the solution. The point where the solvent cannot dissolve the solute anymore and has dissolved the maximum amount of solute at that particular temperature is called the saturation point of the solution. It is not a rigid point and can be altered by the alteration in temperature, that is, increased by the increase in temperature and decreased by the decrease in temperature.  Solubility refers to the capacity of a solution to dissolve solute at a given temperature. The saturation point depends on the solubility of the solution.

Concentrated Solution vs Dilute Solution

A solution with a significant quantity of solute dissolved in its solvent is called a concentrated solution. Dilute solution, on the other hand, refers to a solution with very little solute dissolved in the solvent.

The terms concentration and concentrated solution have relatively different relevant meanings. The former talks about the amount of solute dissolved whereas the latter refers to a particular solution with a high concentration.  It is clear the two should not be confused with each other; the terms cannot be used interchangeably in this case.

If the solute is kept on being added to a concentrated solution to the point where it has reached the saturation point (the point where it cannot dissolve anything anymore) at that particular temperature, the solution becomes saturated.  However, if two identical solutions are taken to their saturated points at two different temperatures, the saturated solution at the lower temperature will be dilute, when compared to the other solution.

In order to dilute the solution, the easiest method is to raise the temperature to increase the saturation point. Also, removing some quantity of the solute also diluted the solution.  On the other hand, to concentrate a solution, either more solute can be added or some quantity of solvent can be removed. Decreasing the temperature also increases the concentration of the solution as it lowers the saturation point.  It can even be observed that on reducing the temperature, some of the solutes which were earlier dissolved gets condensed and appear as crystals. This process is known as crystallisation and has several applications.

Actually, the reason why temperature affects saturation is related to the concept of temperature. Temperature can be visualised as the kinetic energy of particles at the molecular level. When the temperature is increased, the kinetic energy of solvent particles increases and more space becomes available for the solute particles to squeeze through. This is similar to how a jar is shaken slightly so that more contents can be fit in the seemingly occupied jar.

Uses

1. The solution used for melting salt-brine is a saturated solution of sodium chloride.
2. Concentrated acids are used for toilet cleaning.
3. Paints are dilute solutions of various chemicals.
4. Detergents, used at home are also an example of diluted solutions.

Differences and Comparison

Definition

1. Concentrated solution- It is a solution with a large amount of solute dissolved I it.
2. Dilute Solution- It is a solution with low amounts of solute dissolved in it.

Concentration of Solute

1. Concentrated solution- High
2. Dilute solution-Low

Methods

1. Concentrated solution- Remove some solvent or add more solute to concentrate the solution. Temperature can also be decreased.
2. Dilute solution- Remove some solute or add more solvent to dilute the solvent. Temperature can also be increased.

Examples

1. Concentrated solution- Acid used for cleaning bricks.
2. Dilute Solution- Detergent

Conclusion

Concentration refers to the amount of solute dissolved in a solution. A concentrated solution is one, in which the amount of solute dissolved is relatively high. A dilute solution has the quantity of solute dissolved comparatively lower.