What mass of potassium sulfate, K2SO4, is needed to prepare 500. mL of a 0.200 M K2SO4 aqueous solution?
Molarity = moles of solute/ Liters of solution
We have molarity and volume. We can find moles of solute.
500ml (1L/1000ml) = .500L
0.200 = x/.5L
x = .1 moles
Now, we can convert moles to grams.
K2SO4 molar mass is 174.259 g/mol (from the Periodic Table)
0.1moles ( 174.259g/1mol) = 17.4grams