Calculating Molality and Mole Fraction for a 10% (by wt) Solution of KNO3

In summary, molality and mole fraction are both measures of concentration, with molality defined as the number of moles of solute per kilogram of solvent and mole fraction defined as the ratio of moles of one component to the total number of moles in the solution. They can be related through the density of the solution but cannot be used interchangeably due to their different units and purposes. Molality is calculated by dividing moles of solute by mass of solvent in kilograms, while mole fraction is calculated by dividing moles of one component by total moles in the solution.
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Homework Statement


A 10% (by wt) solution of KNO3 would have what molality and what mole fraction


Homework Equations


mole fraction = moles of KNO3/total moles
wt % = # g of solute/total g
molality = # moles KNO3/kg H2O


The Attempt at a Solution


1 g KNO3/10 g total
1 g KNO3/101.1 g/mol = .00989
9 g H2O/18 g/mol = .5 H20

.00989 mol KNO3 / (.00989+.5) = .0194 mole fraction
.00989 moles of KNO3 / .009 kg H20 = 1.1 M
 
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What is molality?

Molality is a measure of the concentration of a solution, defined as the number of moles of solute per kilogram of solvent.

What is mole fraction?

Mole fraction is another measure of concentration, defined as the ratio of the number of moles of one component of a solution to the total number of moles in the solution.

How are molality and mole fraction related?

Molality and mole fraction are both measures of concentration, but they differ in the units used. Molality uses mass units (kg), while mole fraction is a unitless ratio. They can be related through the density of the solution, as molality is often used when the density of the solvent is not known.

Can molality and mole fraction be used interchangeably?

No, molality and mole fraction are two distinct measures of concentration and cannot be used interchangeably. They are based on different units and are used for different purposes.

How do you calculate molality and mole fraction?

Molality can be calculated by dividing the number of moles of solute by the mass of the solvent in kilograms. Mole fraction can be calculated by dividing the number of moles of one component by the total number of moles in the solution.

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