chemistry science about molality and mole fraction

In solution, there are several properties of substances that are solely determined by
the number of solute particles. This property is referred to as the colligative nature of the solution.
Because the colligative nature of the solution is determined by the number of substance particles
dissolved, this chapter will begin with a discussion of concentration
solution.

In the previous lesson, we state concentration by percentage
(%) and molarity (M). In molarity calculations, the quantity of the bottom-
on volume. You certainly remember, volume is a function of temperature (substance will
expand when heated). Because the colligative nature of the solution is affected
temperature, required a quantity that does not depend on temperature. Magnitude
is expressed by mass because the mass is independent of
temperature, both from the quantity of solute and solvent. For that, use
molality that states the number of solute particles (mol) per 1 kg of solvent
(not a solution). Solution made from 1 mole of deep dissolved NaCl
1,000 g of water is expressed as a 1 molal solution and is given a symbol of 1 m NaCl.
Molality is defined by a weighted equation

Number of moles of mass solute 1,000 Molality () = or = × Number of kilograms of solvent p

Information:
m = molality (mol / kg)
Mr. = molar mass of solute (g / mol)
mass = mass of solute (g)
p = mass of solvent (g)
Molality is also useful in other circumstances, such as solvents
is a solid at room temperature and can only be measured in mass,
not its volume so it is impossible to be expressed in form
molarity. Consider the following example of molecular determination.