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SolutionsSolutions

http://www.mhhe.com/physsci/chemistry/essentialchemistry/flash/molvie1.swf

http://www.chemistryland.com/CHM151W/11-PropertiesOfSolutions/Colligative.html

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• I stored sodas in a small refrigerator. One day I noticed that the Diet Coke had exploded from freezing but the regular Coke did not freeze and therefore did not explode.

• I thought why did the Diet Coke freeze and not regular Coke?

• Regular coke has about 39 grams of sugar dissolved in it.

• The 39 grams of sugar interfered with the water trying to freeze. So the freezing point of regular Coke was lower than that of Diet Coke.

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DefinitionsDefinitions

A solution is a mixture of 2 or A solution is a mixture of 2 or more substances in a single more substances in a single phase. phase.

solute + solvent=> solutionsolute + solvent=> solution

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Parts of a Solution• SOLUTE – the

part of a solution that is being dissolved (less amount)

• SOLVENT – the part of a solution that dissolves the solute ( greater amount)

Solute Solvent Example

solid solid

solid liquid

gas liquid

gas gas

5Concentration of a Concentration of a SolutionSolution

Concentration of a Concentration of a SolutionSolution

The amount of solute in a solution is The amount of solute in a solution is given by its given by its concentrationconcentration, or , or molaritymolarity

M = n / V and n = m / MMM = n / V and n = m / MM

Molarity (M) = moles soluteliters of solution

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PROBLEM: PROBLEM: Dissolve 5.00 g of NiCl Dissolve 5.00 g of NiCl22 in in enough water to make 250 mL of solution. enough water to make 250 mL of solution. Calculate the Molarity.Calculate the Molarity.

PROBLEM: PROBLEM: Dissolve 5.00 g of NiCl Dissolve 5.00 g of NiCl22 in in enough water to make 250 mL of solution. enough water to make 250 mL of solution. Calculate the Molarity.Calculate the Molarity.

Step 1: Step 1: Calculate moles Calculate moles of NiClof NiCl22

Step 2: Step 2: Calculate MolarityCalculate Molarity

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USING MOLARITYUSING MOLARITYUSING MOLARITYUSING MOLARITY

What mass of oxalic acid, What mass of oxalic acid, HH22CC22OO44, is, is

required to make 580 mL of a 0.0500 Mrequired to make 580 mL of a 0.0500 Msolution?solution?

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Percent SolutionsDensity = mass / volume d H2O = 1g/ mL

1. Volume/Volume

When both solute and solvents are liquids.

Percent by volume( % v/v) = volume of solute x 100%

______________

volume of solution

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• What is the percent by volume of ethanol in the final solution when 85mL of ethanol is diluted with 250 mL of water?

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• A bottle of the antiseptic hydrogen peroxide, H2O2 is labeled 3.0 %(v/v). How many mL of hydrogen peroxide are in a 2 L bottle of this solution?

• What is the molarity?

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2. Mass / Mass

• When both solute and solvent are solids.

Percent by mass( % m/m) = mass of solute x 100%

______________

mass of solution

• How many grams of potassium sulfate are required to make 1500g of a 5% m/m solution?

• How much water?

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3. Mass/ Volume ( % m/v)

Percent ( % m/v) = mass of solute x 100%

_____________

volume of solution

18 g of ethanol dissolves in 400 mL of water. What is the concentration in % m/v ?

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Making Dilutions

M1 V1 = M2 V2

Where:M1 = concentration of the first solutionV1 = volume of the first solutionM2 = concentration of the second solutionV2 = volume of the second solution

Examples:

1.How many mililiters of a solution of 4M KI are needed to prepare 400 mL of a 0.76 M ?

2. How much water would I need to add to 500 mL of a 2.4 M KCl solution to make a 1.0 M solution?

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• 3) How much 0.05 M HCl solution can be made by diluting 250 mL of 10 M HCl?

•  

•  

•  

• 4) I have 345 mL of a 1.5 M NaCl solution. If 100 mL of water evaporates, what will the molarity of the solution be?

•  

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• If I add 15g of CaCl2 to a flask and complete to a final volume of 500 mL,

• A) What is the % by mass?

• B) What is the molarity of the solution?

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Question 12

• If I make a solution by adding water to 35 mL of methanol until the final volume of the solution is 275 mL…

• a) What is the molarity of methanol in this solution? (The density ofmethanol is 0.792 g/mL)

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• http://instruct.westvalley.edu/harrison/chem30A/worksheets/soultionsworksheet.pdf