solution concentrations. percent by mass (m/m) mass of solute mass of solution ×100solution =...

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Page 1: Solution Concentrations. Percent by Mass (m/m) Mass of solute Mass of solution ×100Solution = solute + solvent

Solution Concentrations

Page 2: Solution Concentrations. Percent by Mass (m/m) Mass of solute Mass of solution ×100Solution = solute + solvent

Percent by Mass (m/m)

Mass of soluteMass of solution

×100 Solution = solute + solvent

Page 3: Solution Concentrations. Percent by Mass (m/m) Mass of solute Mass of solution ×100Solution = solute + solvent

Example 1

An aquarium must contain 13.6 g NaCl per 100.0 g of water. What is the percent by mass (m/m) of NaCl in the solution?

Solute:13.6g (smaller #)

Solvent: 100.0g (larger #)

Solution: 113.6g

+13.6

113.6×100 = 11.97% ≈ 12.0%

solut

esolve

nt

Mass of soluteMass of solution

×100

Water is

always a

solvent!

!!

Page 4: Solution Concentrations. Percent by Mass (m/m) Mass of solute Mass of solution ×100Solution = solute + solvent

Example 2

You have a 650.0g KCL solution. If the percent by mass is 1.25% (m/m), how many grams of solute is in the solution? How many grams of solvent are in the solution?

Solution: 650.0g

Solute: 8.13g

Solvent = 641.87g ≈ 642g

solute650.0

×100 = 1.25%

Solute = 8.13g

First find solute:

Then remember: solute + solvent = solutionand solve for solvent

Page 5: Solution Concentrations. Percent by Mass (m/m) Mass of solute Mass of solution ×100Solution = solute + solvent

Percent by Volume (v/v)

Volume of solute

Volume of solution

×100 Solution = solute + solvent

Page 6: Solution Concentrations. Percent by Mass (m/m) Mass of solute Mass of solution ×100Solution = solute + solvent

Example 3

What is the percent by volume of ethanol in a solution that contains 45mL of ethanol dissolved in 145mL of water?

Solute: 45mL (smaller #)

Solvent: 145mL (larger #)

Solution: 190mL

+45

190×100 = 23.68% ≈ 24%

solven

tsolute

Then remember: solute + solvent = solutionand solve for solvent

Page 7: Solution Concentrations. Percent by Mass (m/m) Mass of solute Mass of solution ×100Solution = solute + solvent

Example 4

If you have 200.0 mL of a 35.0% aqueous solution of ethanol, what volume of ethanol and water are in the solution?

Solution: 200.0mL

Solute: 70.0mL

Solvent = 130.0mL

≈ 130. or 1.3×102 mL

solute200.0

×100 = 35.0%

Solute = 70.0mL

Means dissolved in water; water is the solvent

First find solute:

Page 8: Solution Concentrations. Percent by Mass (m/m) Mass of solute Mass of solution ×100Solution = solute + solvent

Parts Per Million (ppm)

SoluteSolution

×1061 ppm = 1mg/L

Page 9: Solution Concentrations. Percent by Mass (m/m) Mass of solute Mass of solution ×100Solution = solute + solvent

Example 5

If 25 grams of a chemical is dissolved in 75 grams of water, what is the concentration of the chemical in parts per million (ppm)?

Solute: 25g (smaller #)

Solvent: 75g (larger #)

Solution: 100g

+

25100

×106 = 250,000 or 2.5×105 g

Page 10: Solution Concentrations. Percent by Mass (m/m) Mass of solute Mass of solution ×100Solution = solute + solvent

Example 6

Suppose 17 grams of sucrose is dissolved in 183 grams of water. What is the concentration of sucrose in ppm?

Solute: 17g (smaller #)

Solvent: 183g (larger #)

Solution: 200g

+

17200

×106 = 85,000 or 8.5×104 g

Page 11: Solution Concentrations. Percent by Mass (m/m) Mass of solute Mass of solution ×100Solution = solute + solvent

Example 7

150 mL of an aqueous sodium chloride solution contains 0.0045g NaCl. Calculate the concentration of NaCl in parts per million (ppm). Remember 1ppm = 1 mg/L

0.0045g 1000mg 1000mL 150mL 1g 1L

= 30 mg/L = 30 ppm

So change the mL into L and the g

into mg

Page 12: Solution Concentrations. Percent by Mass (m/m) Mass of solute Mass of solution ×100Solution = solute + solvent

Example 8

Convert 0.0035% NaCl by mass into parts per million of NaCl.

* Think of 0.0035% like your grade on a test; 0.0035% means 0.0035 out of 100

0.0035100

×106 = 35ppm