Question

solid mixture was prepared by mixing 1 mole of sodium chloride with 0.2 mole of potassium cholride determine mass percentage of potassium choleide and round off to nearest whole no.​

Answer 1

Answer:   Learning Objective

Calculate the mole fraction and mole percent for a given concentration of mixture

Key Points

Mole fraction describes the number of molecules (or moles) of one component divided by total the number of molecules (or moles) in the mixture.

Mole fraction is useful when two reactive components are mixed together, as the ratio of the two components is known if the mole fraction of each is known.

Multiplying mole fraction by 100 gives mole percent, which describes the same thing as mole fraction, just in a different form. Mole fractions can be generated from various concentrations including molality, molarity and mass percent compositions.

Terms

mole fractionThe ratio of the number of moles of one component in a mixture to the total number of moles.

moleThe SI base unit for the amount of a substance; the amount of substance that contains as many elementary entities as there are atoms in 0.012 kg of carbon-12.

Mole Fraction

In chemistry, the mole fraction, xi, is defined as the amount of moles of a constituent, ni, divided by the total amount of moles of all constituents in a mixture, ntot:

x

i

=

n

i

n

t

o

t

Mole fractions are dimensionless, and the sum of all mole fractions in a given mixture is always equal to 1.

Properties of the Mole Fraction

The mole fraction is used very frequently in the construction of phase diagrams. It has a number of advantages:

It is not temperature dependent, as opposed to molar concentration, and does not require knowledge of the densities of the phase(s) involved.

A mixture of known mole fractions can be prepared by weighing the appropriate masses of the constituents.

The measure is symmetric; in the mole fractions x=0.1 and x=0.9, the roles of ‘solvent’ and ‘solute’ are reversible.

In a mixture of ideal gases, the mole fraction can be expressed as the ratio of partial pressure to total pressure of the mixture.

Answer 2

Given: The solid mixture was prepared by mixing $1$moles of sodium chloride with $0.2$moles of potassium chloride.

We have to determine the mass percentage of potassium chloride.

As we know that the mass of solute for the sodium chloride $=58.5$g.

$1moles$ of sodium chloride is added to the mixture that is $1\times58.5=58.5g.$

As we know that the molecular weight of potassium chloride $=74.5513 g/mol$

And $0.2$moles of potassium chloride is added to the mixture that is $0.2\times74.55=14.91g.$

Now, the mass of the solution$=>58.5g.+14.91g.$

$=>73.41g.$

The concentration of the solution in terms of mass percentage will be,

$=>\frac{Mass of potassium chloride}{mass of solution \times100}\\\\=>\frac{14.91}{73.41\times100} \\\\=>2.031$        

$=>20.3$%

Hence, the mass percentage of potassium chloride will be $20.3$%