Question

What is the mole fraction of the solute in a 2.5m aqueous solution?

Answer 1

Molality is also referred to as molal concentration. It is a measure of the concentration of solutes in a solution. The solution is made up of two parts: solute and solvent. The concentration of a solution can be expressed in a variety of ways, including molarity, molality, normality, formality, volume percentage, weight percentage, and part per million.

Complete answer:
According to the question, $2.5$molal aqueous solution means $2.5$ moles of solute in $1kg$ solvent,
= moles of solute=$2.5$
moles of water= \dfrac{{Given\,mass}}{{molar\,mass}}$$$$$$ 1 kg$= 1000$g$molar mass of water = 18 moles of water=$\dfrac{{1000}}{{18}} = 55.55,$Therefore, so now mole fraction will be equal to${x_i} = \dfrac{{{n_i}}}{{{n_{total}}}}$So$0.043$is the mole fraction of the solute in a 2.5M aqueous solution. The mole fraction or molar fraction (xi) in chemistry is defined as a unit of the amount of a constituent (expressed in moles), ni, divided by the total amount of all constituents in a mixture (also expressed in moles), ntot. The expression can be written as =${x_i} = \dfrac{{{n_i}}}{{{n_{total}}}}$$
The sum of all the mole fractions is equal to 1.
The same concept expressed with a denominator of 100 is the mole percent, molar percentage, or molar proportion (mol%).

Note:
The amount fraction is another name for the mole fraction. It is the same as the number fraction, which is defined as the number of molecules of one constituent Ni divided by the total number of molecules Ntot. Instead of a Roman x, the mole fraction is sometimes denoted by the lowercase Greek letter (chi). The letter y is recommended by IUPAC for gas mixtures.