Question

What is the number of moles of solute in a 0.3 molal solution containing 0.10 kg of solvent? Don't forget the unit.

Answer 1

The number of moles of solute in a 0.3 molal solution containing 0.10 kg of solvent is 0.03.

Step-by-step explanation:

Molality (m) is the number of moles of solute that are dissolved in 1 kilogram of solvent.

Molality is then determined by the expression:

`Molality (m)=(number of moles of solute)/(kilograms of solvent)`

Molality is expressed in units
`(moles)/(kg)`.

Then you can apply a rule of three as follows to calculate the amount of moles of solute: if, according to the given molality, 1 kg of solution has 0.3 moles of solute, 0.10 kg of solution how many moles of solute are there?

`moles=(0.10 kg*0.3 moles)/(1 kg)`

moles=0.03

The number of moles of solute in a 0.3 molal solution containing 0.10 kg of solvent is 0.03.

Answer 2

Molality is one way of expressing concentration for solutions. It has units of moles of solute per kg of solvent. From the given values, we easily calculate for the moles of solute by multiplying the mass of solvent to the molality. We do as follows:

moles solute = 0.3 (10) = 3 mol solute