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Published byBrice Richard Modified over 5 years ago

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Concentration – amount of solute per quantity of solvent Ways to express the concentration of a solution 1.Concentration as a Mass/Volume Percent 2.Concentration as a Mass/Mass Percent 3.Concentration as a Volume/Volume Percent

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Mass/Volume Percent Mass of solute dissolved in a volume of solution, expressed as a % Mass/volume percent =x 100% Example: Saline solution contains 0.9g of sodium chloride dissolved in 100 mL of solution or 0.9% Mass of solute (in g) Volume of solution (in mL)

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A pharmacist adds 2.00 mL of distilled water to 4.00g of a powdered drug. The final volume of the solution is 3.00 mL. a.What is the percent (m/v) of the solution? Mass/volume percent= x 100% = x 100% mass of solute (in g) Volume of solution (in mL) 4.00 g 3.00 mL = 133%

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Use ratios or cross out units to solve for the mass of solute in 100 mL = x = x 100 mL 4.00 g 3.00 mL 4.00g x 100 mL 3.00 mL b. What is the concentration of the drug in g/100 mL of solution? 133% means 133g/100 mL of solution X =4.00g x 100ml x 1 3.00ml = 133 g

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Many people use a solution of trisodium phosphate to clean walls before putting up wall paper. The recommended concentration is 1.7% (m.v). What mass of TSP is need to make 2.0 L solution? (m/v) percent = x 100% rearrange the equation to solve for mass of solute Mass of solute= = Mass of solute (g) Volume of solution (in mL) (m/v) percent x volume of solution 100% 1.7% x 2000 mL 100% = 34 g

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Concentration as a Mass/Mass percent Mass/mass percent gives the mass of a solute divided by the mass of a solution -also referred to as percent (m/m) Mass/mass percent = x 100 % Mass of solute (in g) Mass of solution (in g)

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Calcium chloride can be used instead of road salt to melt the ice on roads during the winter. To determine how much calcium chloride had been used on a road, a student took a sample of slush to analyze. The sample had a mass of 23.47 g. When the solution was evaporated, the residue had a mass of 4.58 g. What was the mass/mass percent of calcium chloride in the slush? Mass/mass percent = x 100% = x 100% = The mass/mass percent was 19.5% (m/m) 19.5 g of calcium chloride was dissolved in 100 g of solution Mass of solute (in g) Mass of solution (in g) 4.58 g 23.47 g 19.5 %

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Concentration as a Volume/Volume Percent Volume/volume percent gives the volume of solute divided by the volume of solution Also referred to as percent (v/v), volume percent concentration Volume/volume percent = x 100% volume of solute (in mL) Volume of solution (in mL)

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Rubbing alcohol is commonly used as an antiseptic for small cuts. It is sold as 70% (v/v) solution of isopropyl alcohol in water. What volume of isopropyl alcohol is used to make 500 mL of rubbing alcohol? Using this equation, Volume/volume percent = x 100 % Rearrange to solve for volume of solute: Volume of solute = = 350 mL of isopropyl alcohol is used to make 500 mL of 70% (v/v) rubbing alcohol. volume of solute Volume of solution Volume/volume % x volume of solution 100% 70% x 500 mL 100% = 350 mL

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Concentration in parts per million or parts per billion ppm – parts per million ( 10 6 ) (one part solute per million parts of solution) ppb – parts per billion (10 9 ) (one part solute per billion parts of solution) Usually mass/mass relationships ie. The mass of solute compared with the mass of solution. ppm = x 10 6 OR mass of solute (g) Mass of solution (g) Mass of solute Mass of solution x g 10 6 g of solution =

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Mercury poisiong becomes apparent when a person build up more than 20.mg of Mercury in their body. Express this amount as ppm for a 60.kg person You must first convert everything into grams 20mg/1000g = 2.0 x 10 -2 g 60kg x 1000g = 6.0 x 10 4 g Ppm = mass solute x 10 6 mass solution = 2.0 x 10 -2 g x 10 6 6.0 x 10 4 g = (3.33 x 10 -7 g) x 10 6 =.33 ppm

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Homework Pg 376 #21-30, pg 378 #31,39

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