Molality Examples

Molarity is very important in chemistry for one big reason. It is the measurement of concentration in any mixture. The molarity of any solution is a way to know the specific elements or compounds which are present in any solution.

The main difference between molarity and normality is that molarity is the number of moles of a compound present in a mixture of compounds whereas normality is the number of gram equivalents of a compound present in a mixture of compounds.

Discussion revolves around molality and its example, the difference between molarity and molality and molal depression constant.

What is the difference between Molarity and Molality

Molarity refers to the measurement of moles in relation to the total volume of the solution, whereas molality refers to the measurement of moles in relation to the mass of the solvent.

Only in its denominator does molality differ from molarity. While molarity is measured in liters of solution, molality is measured in kilos of solvent.

Concentrations stated in molality are widely used to investigate the characteristics of solutions that are affected by changes in vapour pressure and temperature. 

Molality is frequently employed since its value does not vary when the system’s temperature changes, making it an independent quantity. The volume of a solution, on the other hand, is temperature dependant.

Molality and molarity are linked in value for dilute aqueous solutions because their density is close to 1.0 g/mL. This means that 1.0 L of the solution has a mass of about 1.0 kg. As the solution becomes more concentrated, its density will be less than 1.0 g/ml, and the molality value will diverge from the molarity value.

What are some Molality Examples?

Molecular concentrations are used when analyzing solution characteristics in relation to vapor pressure and temperature changes. Because its value does not alter with changes in temperature, molality is used. The volume of a solution, on the other hand, is influenced by temperature only minimally.

Example 1: 12g of urea (NH₂CONH₂) was dissolved in 100g of water. Then Calculate the Molality of the Solution.

Give, 

Mass of solute = 12g , Mass of solvent = 100g

Mass of Urea = 14+2+12+16+14+2= 60g

No. of moles of solute= 12/60= 0.2

Molality= no. of moles of solute/mass of solvent in kg

Molality = 0.2/0.1

Molality= 2m

What is the molal solution?

Solvents with a molecular weight of one molal per kilogram of solute constitute a molal solution. Concentration is the strength of a solution or the amount of dissolved substance in a given volume of solvent. Molality (m) represents a solution’s concentration.

What is the formula for the molal solution?

Molality = n(no. Of moles of Solute)/ m (mass of solvent in kg) = m(mass of solute in gm) / {W(molar mass of solute)* m (mass of solvent)}

nsolute represents the amount of the solute (in moles)

msolvent specifies the mass of the solvent (in kilograms)

msolute represents the mass of the solute (in grams)

W solute represents the mass of the solute (in g/mol).

What is the molal depression constant?

The molality (m) of the solute times a proportionality constant called the molal freezing point depression constant has been calculated to be the freezing point depression of nonelectrolyte solutions.

The depression in the freezing point can be expressed as the difference between the boiling point of the pure solvent and the boiling point of the solution

∆Tf =T0f-Tf

A drop in freezing point is also directly related to molality ‘m’, as is an increase in boiling point.

∆Tf = 1000 x kf x m2 / M2 x m1

Where,

k f = molal depression constant, m2 is the mass of solvent in g, M1 is the mass of solvent in kg, and M2 is the molar mass of solute.

Conclusion

In the whole Molality, Molarity and Mole fraction concept learn the formula, factors on which it depends. Focus on the calculations in numerical and remember all the properties and examples of Molality, Molarity, and Molality.

The molal depression constant, denoted as K f, is the depression at the freezing point in a solution containing 1 gm mole of solute dissolved in 1000 gm of solvent.

An equal amount of solute can be dissolved per kilogram of solvent to calculate the concentration of a solution. Molalities are denoted by the symbol m.

molality = moles of solute/ mass of solvent in kg

m = n(solute) /mass(solvent in kg)