what is the molality of a solution made up of 20.5 grams of potassium chloride in 750 grams of water?
molality = #moles/kg solvent
moles = grams/molar mass. Solve for moles and subsitute into the first equation. Kg water = 0.750
To find the molality (m) of a solution, you need to divide the moles of solute by the mass of the solvent (in kilograms).
Here's how to calculate the molality of the given solution:
Step 1: Convert the mass of potassium chloride to moles.
To do this, divide the given mass of potassium chloride by its molar mass. The molar mass of potassium chloride (KCl) is 74.55 g/mol.
Number of moles = mass of KCl / molar mass of KCl
mass of KCl = 20.5 g
molar mass of KCl = 74.55 g/mol
Number of moles of KCl = 20.5 g / 74.55 g/mol
Step 2: Convert the mass of water to kilograms.
The given mass of water is 750 grams, and to determine the molality, it needs to be in kilograms.
Mass of water = 750 g = 750 g / 1000 g/kg
Step 3: Calculate molality using the obtained values.
Molality (m) = number of moles of KCl / mass of water (in kg)
Plug in the values:
Molality (m) = (20.5 g / 74.55 g/mol) / (750 g / 1000 g/kg)
Now, you can calculate the molality of the solution by performing the above calculation.