Difference Between Solution and Suspension

Main Difference – Solution vs Suspension

Solutions and suspensions are both considered as mixtures. The key difference between solution and suspension is their particle size. Particles in a solution are much smaller than that of suspensions. Due to this difference between solute particles and suspension particles, there are distinct differences in the two systems. However, the components of both the systems are not chemically bonded to each other and can be separated based on their physical properties such as size, solubility and density.

This article explains,

1. What is a Solution?
      – Definition, Characteristics, Examples

2. What is a Suspension?
      – Definition, Characteristics, Examples

3. What is the difference between Solution and Suspension?

What is a Solution – Definition, Characteristics, Examples                      

A solution is a homogeneous mixture of two substances. The most abundant component of the system is known as the solvent whereas solute is the substance which is dissolved in the solution. The solute particles are in either atomic or molecular level. The size of solute particles is usually < 1 nm. Solvents and solutes are in the same phase and cannot be distinguished even under a light microscope. The homogeneity of solutions arises from the fact that the solutes are evenly distributed in the solvent. The components of a solution system are comparatively difficult to be separated than that of suspensions or colloids.

Ex: NaCl is a white solid. After dissolving it in water, you cannot see the white solid anymore. Instead, you will only see the transparent solution.

Solutions are transparent due to the small size of solute particles, which prevent the reflection or scattering of light. Solutions, at a given temperature, are stable and remain homogeneous without particles settling.

The formation of solutions depends on the affinity of the solutes to the solvent. Polar solutes dissolve only in polar solvents and non-polar solutes dissolve only in non-polar solvents. Water is the most known polar solvent. Polar solutes such as salt, sugar, KCl are dissolved easily. Most organic solvents such as benzene, hexane and petroleum ether are non-polar. Iodine and Styrofoam can be given as examples of non-polar solvents.

Some examples of solutions can be given as follows;

Gas in Gas: Air

Gas in liquid: Soda

Liquid in liquid: Water and alcohol

Solid in liquid: NaCl in water

Liquid in solids: Mercury amalgam, mercury in silver

Solids in solids: Alloys, steel, brass, bronze

What is a Suspension – Definition, Characteristics, Examples

Particles of suspensions are often greater than 1000 nm. Therefore suspensions are heterogeneous. They are not of one phase. When soil is mixed with water, large soil particles can be clearly seen and distinguished from water. This system is a typical suspension. Particles in a suspension tend to travel through the medium and undergo sedimentation with time. Due to the large sizes of particles, they can be easily separated by filtration. Suspensions are cloudy, unlike solutions due to bigger particle size. Light is scattered or reflected by these particles.

Most known suspensions are formed by suspending solid particles in liquids (ex-: muddy water, CaCO₃ in water). However, there can be incidents of liquid-liquid suspensions (mercury in oil/water), solid-gas suspensions (soot in air). Emulsions are a form of suspensions where two immiscible liquids are shaken together to form a cloudy mixture. When this is let to stand, the separation of two liquid layers is easily seen. Oil and water together is one fine example for emulsions.

Some oral medicines are available as suspensions. For example, milk of magnesia which is used for antacid treatments is a suspension of magnesium hydroxide.

Suspensions are not of one phase. There can be a phase separation if the system is left to stand for some time. Hence, these are not stable.

Difference Between Solution and Suspension

Composition

Solution: Solutions are homogeneous ( the composition is the same throughout). Solute particles are dissolved in a solvent and are evenly dispersed.

Suspension: Supensions are heterogeneous. Particles can be visibly distinguished and particle dispersion is not even.

Particle Size

Solution: Particle size is <1 nm. They are comparatively very small and either of an atomic or molecular level. They cannot be seen even under a light microscope.

Suspension: Particle size is >1000 nm. Particles are comparatively very large and can be seen by naked eye. They can be present as coagulations.

Properties

Solution: Solutes and the solvent are in the same phase.

Suspension: Suspended particles can be in a different phase than the medium.

Appearance

Solution: Solutions are transparent. There is no scattering of light. 

Suspension: Suspensions are cloudy. Light can be reflected or scattered.

Examples

Solution: Examples include NaCl in water and sugar in water.

Suspension: Examples include milk of magnesia, soot in the air.

Reference List:

Image Courtesy:

“Chemical precipitation diagram” By Vectorized by ZooFari; raster by ZabMilenko – Own work, Chemical precipitation diagram.png (Public Domain) via Commons Wikimedia

 “652201” (Public Domain) via Pixabay