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DMA #8 5/6/11
When talking about a liquid-what does the word “solution” mean?
Solution
A homogeneous mixture of two or more substances in a single physical state Liquid Solid Gas
Classification of Matter
Solutions are homogeneous mixtures
Solute
A solute is the dissolved substance in a solution.
A solvent is the dissolving medium in a solution.
Solvent
Salt in salt water Sugar in soda drinks
Carbon dioxide in soda drinks
Water in salt waterWater in soda
Properties of Solutions
Solubility can apply to different states of matter. Ability to dissolve.
Soluble – a substance that is able to dissolve in another substance. Sugar in water Salt in water
Insoluble – A substance that does not dissolve in another substance. Oil in water
Solutions
Solid solutions Alloys – two or more metals
Gaseous solutions Air
Liquid solutions Oxygen in water Vinegar (acetic acid in water)
Aqueous solutions Ions in water
“Like Dissolves Like”
Fats Benzene Steroids Hexane Waxes Toluene
Polar and ionic solutes dissolve best in polar solvents
Nonpolar solutes dissolve best in nonpolar solvents
Inorganic Salts Water
Sugars Small alcohols
Acetic acid
Therefore…
Solids tend to dissolve best when:
o Heatedo Stirredo Ground into small particles
Liquids tend to dissolve best when:
o The solution is coldo Pressure is high
Saturation of Solutions
A solution that contains the maximum amount of solute that may be dissolved under existing conditions is saturated.
A solution that contains less solute than a saturated solution under existing conditions is unsaturated.
A solution that contains more dissolved solute than a saturated solution under the same conditions is supersaturated.
Your Task
Do the following in your notebooks:
15-1 Section Review questions #1-4, pg. 505
On pg. 532 do the “Concept Mapping” activity
DMA #1 5/9/11
What is a solute and what is a solvent?
Concentration of Solutions
The concentration of a solution is the amount of solute in a given amount of solvent or solution.
Calculations of Solution Concentration
Molarity - the ratio of moles of solute to liters of solution
Molarity=M= moles of solute Liters of solution
Calculations of Solution Concentration You need to be able to calculate
molarity Example:
What is the molarity of a solution formed by mixing 10.0g H2SO4 with enough water to make 100.0mL of solution?
To solve: Moles of solute?
▪ 10.o g H2SO4
Liters of solution?▪ 100.0mL
Calculations of Solution Concentration How do we solve it?
convert our units Divide solute by solution’s total volume
mL L Gramsmoles 10.0g H2SO4 1mol H2SO4 Answer 1.02 M0.100 L solution
98.1 g H2SO4x
Calculations of Solution Concentration
Practice #1 Vinegar is a solution of acetic acid.
What is the molarity of the solution when 125 g of acetic acid (C2H4O2) is dissolved in enough water to make 1.50 L of solution?
Answer 1.39M
Calculations of Solution Concentration
Practice #2 How many grams of bromine are
needed to prepare 0.500 L of a 0.0100 M solution of bromine in water?
Answer 0.799 g
Beer’s Law Lab
To learn more about molarity and how to calculate it we will be doing a lab!
Beer’s Law (named after a person, not a beverage) states that you can determine the concentration of a solution by how much light it absorbs.
So, you will be making solutions of different concentrations and testing them
Beer’s Law Lab
Important to remember Your measurements and calculations
must be exact! If you do not measure right, you will ruin
your solution and you will have to begin again
You will do a graph-this MUST be done on graph paper or by computer-NO exceptions
Calculations of Solution Concentration
Mole fraction – the ratio of moles of solute to total moles of solution
BA
AA nn
nAoffractionMole
DMA #2 5/10/11
Calculate the Molarity of 98 grams of sodium hydroxide in 2.2 liters of solution.
Beer’s Law Lab
Getting started: Create a data table Make up your solution
This is from the calculations you made yesterday
50 mL total You will use this to create all the
dilutions T0 make your dilutions:
M1V1=M2V2
Beer’s Law Lab
After you create the dilutions you will place a sample of your solution in the colorimeter
You will graph your results-on graph paper
