Define term molarity of a solution write one disadvantage in using the molarity as the unit of concentration
Answers
Explanation:
In chemistry, molarity is a concentration unit, defined to be the number of moles of solute divided by the number of liters of solution.
Units of Molarity
Molarity is expressed in units of moles per liter (mol/L). It's such a common unit, it has its own symbol, which is a capital letter M. A solution that has the concentration 5 mol/L would be called a 5 M solution or said to have a concentration value of 5 molar.
Answer:
Molarity is defined as the moles of a solute per liters of a solution. Molarity is also known as the molar concentration of a solution.
Molality is one of the important properties of solutions. It is used to express the concentration of a solute in a solution and mostly depends on the mass of the solvent. Molality is also sometimes referred to as molal concentration. It is usually denoted by the letter “m”.
The concept of molality was basically framed as a relation to molarity which is described as the molar concentration of a solution. The use of this property was first recorded in the publication authored by G. N. Lewis and M. Randall in the year 1923. The topic was covered in the book titled “Thermodynamics and the Free Energies of Chemical Substances.” We will learn about the concept in detail below.
Molality Definition and Formula
Molality (m) is defined as the number of moles of solute per kilogram of solvent. The formula for molality is given as;
Molality (m) = moles of solute / kilograms of solvent
Students have to remember that molality is used to measure the moles in relation to the mass of the solvent and not the mass of the solution.
Sometimes there are also instances where the solutions contain more than one solvent. In such cases, we consider or define the molality of the mixed solvent. Alternatively, the units are expressed as mole solute per kilogram mixed solvent.
SI Unit of Molality
The SI unit of molality is moles per kilogram (mol/kg). For example, a solution whose molality is given as 6 mol/kg is stated as 6 molal or 6 m.
Advantages and Disadvantages of Using Molality
Talking about the advantages of using molality as a measure of concentration is that molality, as mentioned above, is solely dependent on the mass of solute and the solvent. What it means is that these factors are not affected by changes in temperature or even pressure as in the case of solutions prepared volumetrically. Secondly, it is quite useful because in a solution the molality of one solute is independent of the existence of other solutes.
Coming to the disadvantages, it is not applicable in instances where there is no pure substance in a mixture. For example, mixtures such as water and alcohol or alloys. Here, anyone of the substance can be considered as the solvent.