CHE 1302 Lecture Notes - Lecture 1: Molality, Lead, Mouthwash
Document Summary
Concentration calculations: calculate the % by mass of hno3 in a solution that contains: (a) 5. 00 mol hno3 in 750 g of solution (b) 5. 00 mol hno3 in 750 g of h2o. Calculate the molarity of alcohol in this solution. (assume the density of solute c2h5oh is 0. 789 g/ml). 8. 00 % by volume 8. 00 ml c2h5oh in 100 ml of solution. Since molarity is defined as (mol solute)/(l solution) the 8. 00 ml c2h5oh needs to be converted to a number of moles : mol c2h5oh present. = (8. 00 ml c2h5oh) (0. 789 g c2h5oh/1 ml c2h5oh) (1 mol c2h5oh/ 46. 07 g c2h5oh) = 0. 137 mol c2h5oh in 100 ml of solution molarity = mol. = 1. 37 m: the water in a swimming pool (2. 0 m 4. 0 m 7. 0 m) contains pb2+ ions at a concentration of 2. 5 ppb by mass. What mass of pb2+ is present? (assume the density of h2o is 1. 00 g/ml)
