To understand the solution, let’s first begin with understanding the mixture.
In chemistry, a mixture is the combination of two or more different substances which are not chemically combined, which means that the identities of the substances are retained.
There are three types of mixture:
Suspensions, colloids, and solutions.
Suspensions are a type of heterogeneous mixture in which the solute particles do not dissolve in the solvent. Instead, they get suspended and float around freely throughout the bulk of the solvent. E.g. muddy water, chalk in water, sand in water.
Colloids are also examples of a heterogeneous mixture having an intermediate particle size between those of a solution and a suspension. The dispersed particles are outspread uniformly throughout the dispersion medium, solid, liquid, or gaseous form. E.g. solid aerosol, liquid emulsion.
Here, we’ll discuss solutions.
Mixtures can also be classified as homogeneous and heterogeneous.
Homogeneous mixtures are those in which the components mix entirely with each other, and their composition and properties are uniform throughout the system: E.g. steel, air, natural gas, brass.
Heterogeneous mixtures are those in which the components can be observed separately. Their composition and properties are not uniform throughout the system—E.g. sand & water, concrete, Ice & water, salt & pepper.
A solution is a homogeneous mixture.
A solution is made up of two parts, namely, a solute and a solvent. Generally, the component present in a larger amount is called the solvent, and the other is called the solute.
Properties of solution
It is a homogeneous mixture. Solute particles in a solution are extremely small. It has a diameter of less than 1nm(1nanometre=10–9metre). It is impossible to see the constituent particles of a solution, even with a microscope. The particles of a solution are so small that they pass even through the filter paper. As a result, we cannot use the process of filtration to separate a solution. The solutions are very stable. The solute particles cannot be separated by physical means.
A true solution does not scatter light because of the size of its very tiny sized particles. Solutions can be categorized into different types based on their properties. It can be categorized into the solvent solution, depending upon the dissolution of the solute. Different types of Solutions are:
An unsaturated solution is one in which more solute can be added to a solvent at a given temperature.
A saturated solution can be defined as a solution that contains the maximum amount of solute that can be added to a solvent at a given temperature, i.e., the solvent has reached its limit and cannot dissolve any more solute at a given temperature.
A supersaturated solution has more amount of solute than a solvent can dissolve at a given temperature. The extra solute crystallizes and settles down.
E.g., let’s say 100 ml of water (solvent) can dissolve 30gms of sugar at 30°C.
Now keeping the solvent (water) at 30°C,
If we add 20gms of sugar, it can still dissolve 10gms more, which means it is an unsaturated solution.
If we add 30gms of sugar to the 100ml water, it reaches its maximum capacity to dissolve solute (sugar) and cannot dissolve any more; hence it is a saturated solution. If we add any more sugar to it, it will just settle down & won’t dissolve any further.
If we add more than 30gms of sugar to the 100 ml water, it will not dissolve any more sugar at 30°C. However, if we boil it and say the temperature reaches somewhere 70-80°C now, the sugar will be dissolved (because the space between the water particles will increase due to the heat). Although when the Solution comes back at 30°C, the excess sugar will turn back to crystals. This type of solution is said to be a supersaturated solution.
Depending on whether the solvent is water or not, solutions can be further categorized as:
Aqueous solution – When the solvent is water, the solution is called an aqueous solution.
Water is a polar solvent.
It forms a liquid solution.
E.g., saltwater, rain, sugar in water, and copper sulfate in water.
Non-aqueous solution – A solution in which the solvent is something other than water is called a non-aqueous solution.
The solvent may be polar or nonpolar.
The solution may be solid, liquid, or gas.
E.g., liquid ammonia, Solution of sulfur in carbon disulfide, liquid sulfur dioxide, solution of iodine in carbon tetrachloride, and Ethene in dichloromethane, sulfuryl chloride.
Depending on the amount of solute added to the solvent
A dilute solution can be defined as a solution that contains a comparatively small amount of solute in a large amount of solvent. The process of reducing the amount of solute in a given solution is called dilution. Sometimes it can be achieved just by increasing the amount of solvent in the solution. E.g. such as adding water to soda, or if the lemonade tastes too sour or sweet, we add water to dilute it.
A concentrated solution contains a relatively large amount of solute dissolved in the solvent.
Concentrations of a solution may be calculated using a wide variety of measurement units, each convenient for particular applications.
Molarity (M) is one of the concentration units which is useful for many applications in chemistry. Molarity can be defined as the number of moles of solute in exactly 1 litre (1 L) of the solution and has the units of ‘mol/L’.
Formula to calculate the molarity of a solution,
Molarity will be equal to mol solute/ L of solution.
Based on the concentration of solute
- Hypotonic solution
- Isotonic solution
- Hypertonic solution
- When comparing two solutions with unequal solute concentration,
- The solution with the higher solute concentration is called a hypertonic solution.
- Solutions of equal solute concentration are called isotonic solutions.
- The solution with the lower solute concentration is hypotonic.
Hope you have learnt about the types of solutions in chemistry. Understand the concepts to apply the correct methods to derive the correct solutions in your experiments.
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