Calculate the molality of the solution prepared by dissolving 0.50 g (NH4)2SO4 in 50g H2O
mols (NH4)2SO4 = grams/molar mass = ?
Then m = mols/kg solvent.
To calculate the molality of a solution, you need to know the mass of the solute and the mass of the solvent. In this case, the solute is (NH4)2SO4 and the solvent is H2O.
Step 1: Convert the mass of (NH4)2SO4 to moles.
The molar mass of (NH4)2SO4 is calculated by adding up the atomic masses of its constituent elements:
(N) 14.01 + (H) 1.01 * 8 + (S) 32.07 + (O) 16.00 * 4 = 132.14 g/mol
The moles of (NH4)2SO4 can be calculated using the equation:
moles = mass / molar mass
Given that the mass of (NH4)2SO4 is 0.50 g:
moles = 0.50 g / 132.14 g/mol = 0.0038 mol
Step 2: Convert the mass of H2O to kilograms.
To calculate molality, the mass of the solvent should be in kilograms. Convert the mass of H2O from grams to kilograms:
mass of H2O = 50 g = 50 g / 1000 = 0.050 kg
Step 3: Calculate the molality.
Molality (m) is defined as the moles of solute per kilogram of solvent.
molality = moles / kg of solvent
molality = 0.0038 mol / 0.050 kg = 0.076 mol/kg
Therefore, the molality of the solution prepared by dissolving 0.50 g (NH4)2SO4 in 50 g H2O is 0.076 mol/kg.