Question

How much potassium chloride is needed to make 0.500 m solution with 1.50 L of water?

Answer 1

55.9 g KCl.

Step-by-step explanation:

Hello there!

In this case, according to the definition of molality for the 0.500-molar solution, we need to divide the moles of solute (potassium chloride) over the kilograms of solvent as shown below:

`m=(mol)/(kilograms)`

Thus, solving for the moles of solute, we obtain:

`mol=m*kilograms`

Since the density of water is 1 kg/L, we obtain the following moles:

`mol=0.500mol/kg*1.50kg\\\\mol=0.75mol`

Next, since the molar mass of KCl is 74.5513 g/mol, the mass would be:

`0.75mol*(74.5513g)/(1mol)\\\\55.9g \ KCl`

Regards!