mole fraction of solute is 0.4 what is molality of solution

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To find the molality of a solution, we first need to understand what mole fraction is.

Mole fraction is defined as the ratio of the number of moles of a component to the total number of moles in the solution. It is denoted by the symbol "X" and is calculated using the equation:

Mole fraction of component A (XA) = moles of A / total moles in the solution

In this case, the mole fraction of the solute is given as 0.4. This means that 40% of the total moles in the solution are due to the solute.

Now, let's move on to molality.

Molality (m) is defined as the number of moles of solute per kilogram of solvent. It is denoted by the symbol "m" and is calculated using the formula:

Molality (m) = moles of solute / mass of solvent (in kg)

We are not given the mass of the solvent, so we cannot directly calculate the molality. However, we can still determine it with the given information if we make the assumption that the moles of solute and solvent are equal in this case.

Since the mole fraction of the solute is 0.4, it implies that the mole fraction of the solvent is 0.6 (since the sum of mole fractions in a solution is always equal to 1).

So, if we assume that the moles of solute and solvent are equal, we can say that the mole fraction of the solvent (XB) is also 0.6.

Now, to calculate the molality, we can use the equation for mole fraction:

Mole fraction of component B (XB) = moles of B / total moles in the solution

Since the mole fraction of the solvent (XB) is 0.6 and the mole fraction of the solute (XA) is 0.4, we can set up the following equation:

XB = moles of solvent / (moles of solvent + moles of solute)

0.6 = moles of solvent / (moles of solvent + moles of solute)

Since we assumed that the moles of solute and solvent are equal, we can replace both the moles of solute and solvent with the variable "x":

0.6 = x / (x + x)

0.6 = x / 2x

0.6 = 1 / 2

x = 1

Therefore, the moles of solute and solvent are both 1.

Now, to find the mass of the solvent, we need to use the molecular weight of the solvent. Let's assume the molecular weight of the solvent is 100 g/mol.

Mass of solvent = moles of solvent * molecular weight of solvent

Mass of solvent = 1 * 100 = 100 g

Since molality is defined as the number of moles of solute per kilogram of solvent, we need to convert the mass of the solvent to kilograms:

Mass of solvent (in kg) = 100 g / 1000 = 0.1 kg

Finally, we can calculate the molality using the formula:

Molality (m) = moles of solute / mass of solvent (in kg)

Molality (m) = 1 / 0.1 = 10 mol/kg

Thus, the molality of the solution is 10 mol/kg.