Concentration vs Solubility
Concentration is an important and very common phenomenon in chemistry. This is used to indicate quantitative measurement of a substance. If you want to determine the amount of copper ions in a solution, it can be given as a concentration measurement. Almost all the chemical calculations use concentration measurements to draw conclusions about the mixture. To determine the concentration, we need to have a mixture of components. To calculate the concentration of each component, the relative amounts dissolved in the solution have to be known.
There are few methods to measure the concentration. They are mass concentration, number concentration, molar concentration, and volume concentration. All these measures are ratios where the numerator is representing the amount of the solute, and the denominator is representing the amount of solvent. In all these methods, the way of representing the solute is different. However, the denominator is always the volume of the solvent. In mass concentration, mass of the dissolved solute in one liter of the solvent is given. Likewise, in number concentration, number of solutes and, in molar concentration, moles of solute are given. Further in volume concentration volume of the solute is given. Other than these, concentrations can be given as mole fractions where the moles of the solute are given in relation to the total amount of substances in the mixture. In the same way, mole ratio, mass fraction, mass ratio can be used to indicate concentration. It can also be indicated as percentage values. According to need, a suitable method to indicate the concentration has to be selected. However, the conversion between these units should be known to chemistry students in order to work with them.
Solvent is a substance with dissolving capability, thus can dissolve another substance. Solvents can be in a liquid, gaseous or solid state. Solute is a substance that is soluble in a solvent in order to form a solution. Solutes can be in liquid, gaseous or solid phase. So, solubility is the ability of a solute to dissolve in a solvent. The degree of solubility depends on various factors like the type of solvent and solute, temperature, pressure, stirring speed, saturation level of the solution, etc. Substances are soluble in each other only if they are alike (“likes dissolve likes”). For example, polar substances are soluble in polar solvents but not in non-polar solvents. Sugar molecules have weak inter molecular interactions between them. When dissolved in water, these interactions will break, and molecules will be parted. Bond breakages need energy. This energy will be supplied by the formation of hydrogen bonds with water molecules. Because of this process, sugar is well soluble in water. Similarly, when a salt like sodium chloride dissolves in water, the sodium and chloride ions are released, and they will interact with polar water molecules. The conclusion we can arrive from the above two examples is that, the solutes will give their elementary particles upon dissolving in a solvent. When a substance is first added to a solvent, first it will dissolve rapidly. After sometime a reversible reaction establishes and the dissolving rate will decrease. Once the dissolving rate and the precipitating rate are equal, the solution is said to be at solubility equilibrium. This type of solution is known as a saturated solution.
What is the difference between Concentration and Solubility?
• Concentration gives the amount of substances in a solution. Solubility is the ability of a substance to dissolve in another substance.
• If the solubility of a material is high in a solvent, then its concentration will be high in the solution. Similarly, if the solubility is low, concentration will be low.