What mass (in g) of NH3 must be dissolved in 475 g of methanol to make a 0.250 m solution?

We need 2.02 grams of NH3

Explanation:

Step 1: Data given

Mass of methanol = 475 grams

Molality of the solution = 0.250 M

Molar mass of NH3 = 17.03 g/mol

Molar mass of = methanol = 32.04g/mol

Step 2: Calculate moles NH3

Molality = 0.250 m = mol NH3 / 0.475 kg

moles NH3 = 0.250 molal * 0.475 kg

Moles NH3 = 0.11875 moles

Step 3: Calculate the mass of NH3

Mass NH3 = moles NH3 * molar mass NH3

Mass NH3 = 0.11875 mol * 17.03 g/mol

Mass NH3 = 2.02 grams

We need 2.02 grams of NH3