Solutions Molality

Molality (m) A concentration that expresses the moles of solute in 1 kg of solvent Molality (m) = moles of solute 1 kg solvent

Units of Molality 2.0 m HCl = 2.0 moles HCl 1 kg solvent 6.0 m HCl= 6.0 moles HCl 1 kg solvent

Molality Calculation NaOH is used to open stopped sinks, to treat cellulose in the making of nylon, and to remove potato peels commercially. If 4.0 g NaOH are used with 500. g of water, what is the molality (m) of the solution?

Calculating Molarity 1) 4.0 g NaOH x 1 mole NaOH = 0.10 mole NaOH 40.0 g NaOH 2) 500. g x 1 kg _ = kg water 1000 g mole NaOH = 0.20 mole NaOH kg water 1 kg water = 0.20 m NaOH

Calculating Molality A KOH solution contains 400. g water and 2 mole KOH. What is the molality of the solution? 1) 8 m 2) 5 m 3) 2 m Drano

Solution 2) 5 m M = 2 mole KOH = 5 m 0.4 kg water Drano

Calculating Molarity A glucose solution is made with 2.0 kg water and 72 g glucose (C 6 H 12 O 6 ). If glucose has a molar mass of 180. g/mole, what is the molality of the glucose solution? 1)0.20 m 2)5.0 m 3)36 m

Solution A glucose solution is made with 2.0 kg water and 72 g glucose (C 6 H 12 O 6 ). If glucose has a molar mass of 180. g/mole, what is the molality of the glucose solution? 1)72 g x 1 mole x 1 = 0.20 m 180. g 2.0 kg

Molality & Grams & Volume What is the molality of a solution prepared by mixing 3.0 moles NaOH with sufficient solvent to make a total mass of 400 g? 1)12 m 2)10.7 m 3) 300 m

Solution 2) 3.0 mol x 40 g = 120 g solute 1 mol mass of solvent = 400 g total – 120 g solute = 280 g solvent m = 3.0 mol kg m = 10.7 m