Concentration of Solutions

Concentration measurement that describesmeasurement that describes how much solute in given amount of how much solute in given amount of solvent or solution solvent or solution express concentration using many, many different unitsexpress concentration using many, many different units –pick the unit according to task at hand

Percent by mass by Volume % = part x 100 whole

Twists in Word Problems sometimes ask for part or whole, not percent sometimes give volume/mass of solution sometimes give volume/mass of solvent and volume/mass of solute mass solution = mass solute + mass solvent

ppm (parts per million) used when solute is present in very small amountsused when solute is present in very small amounts (Regents board doesn’t follow this rule) (Regents board doesn’t follow this rule)

ppm (parts per million) ppm = grams solute x 1,000,000 ppm is ratio between mass solute & mass soln like % except the whole is 1,000,000 instead of 100 grams solution

About g of O 2 can be dissolved in 100 mL of water at 20 o C. Express in ppm. [memorize: 1 mL water has mass of 1 g] ppm = g x 1,000, = 43 ppm

CO 2 gas has solubility of g/100 g water at 40 o C. Express in parts per million. ppm = g solute x 1,000, g solution = 971 ppm

What is the concentration in ppm of a solution with 30.0 g NaNO 3 in 70.0 g water? ppm = 30.0 g NaNO 3 x 1,000, g solution = 300,000 = 3.0 X 10 5 ppm

How many grams of KOH are needed to be dissolved in water to make grams of a 10.0 ppm solution? 10 ppm = ? grams KOH X 1,000, g solution ? = 0.02 grams KOH