Question

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

Answer 1

Answer:

55.9 g KCl.

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:

$m=\frac{mol}{kilograms}$

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:

$0.75mol*\frac{74.5513g}{1mol}\\\\55.9g \ KCl$

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