Chapter 8 Solutions When substances dissolve to form solutions the properties of the mixture change 81 A solution is a type of mixture 82 The amount of solute that dissolves can vary 83 Solutions can be acidic basic or neutral ID: 269257
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Unit: Chemical InteractionsChapter 8: SolutionsWhen substances dissolve to form solutions, the properties of the mixture change.
8.1: A solution is a type of mixture
8.2: The amount of solute that dissolves can vary
8.3: Solutions can be acidic, basic, or neutral
8.4: Metal alloys are solid mixturesSlide2
Review / warm-upWhat are their chemical formulas? What are the elements?Which is an ionic compound and which is a covalent compound?Are the properties of each compound the same/different than the atoms/elements that form them?What is the different in how these compounds are held together?
8.1: A solution is a type of mixture
Na
Cl
O
C
O
animationSlide3
8.1 A solution is a type of mixture8.1: A solution is a type of mixtureSlide4
The parts of a solution are mixed evenlyMixture: a combination of substances – ex: fruit salad, chiliCan physically separate ingredients because they are not chemically changed – still the same substancesIf a mixture is so completely blended together…
The ingredients
canNOT
be
separated and identified as different substancesSolution: a type of mixture, called a homogeneous mixture“same throughout” (“well-mixed”)
All portions of the the mixture have the same propertiesSand + Water Sand sinks to the bottom ; Solution?Sugar + water
sugar is dispersed throughout; Solution?Other common solutions: seawater, gasoline, liquid part of blood
8.1: A solution is a type of mixtureSlide5
Solutes and Solvents – components of a solutionSolutions – have a definite compositionSolute – a substance that is dissolved to make a solution
When it dissolves, it separates into individual particles
It is dissolved into the…
Solvent – a substances that dissolves a solute
Most common: water
Others – ex: turpentine, soaps - to remove oilsAfter the solute dissolves and separates into individual particles, it is not possible to identify the solute and solvent as different substancesEx:
8.1: A solution is a type of mixture
SolutionSolutesolvent
Salt water
blood
salt
water
Calcium ions, sugar
waterSlide6
8.1: A solution is a type of mixture
Solvent (water)
animation
Solute (salt)
A salt water solutionSlide7
Types of SolutionsGas Solution: Ex: air = oxygen (an other gases) dissolved in nitrogenLiquid Solution:Ex: vinegar = acetic acid dissolved in waterSolid Solution:
Ex: bronze = tin dissolved in copper
Must first be melted to a liquid, then mixed, then cooled to solid
Mixed?
Ex: soda = carbon dioxide dissolved in water solutionEx: saltwater = salt dissolving in water
8.1: A solution is a type of mixtureSlide8
Solution Worksheet
solute
solvent
solute
solute
solute
solute
solute
solute
solute
solvent
solvent
solvent
solvent
solvent
solvent
solventSlide9
SuspensionsSuspension: the particles added are larger than those found in a solution, so instead of dissolving, these larger particles turn the liquid cloudy
Ex: Flour added to water
Can sometimes separate the components of the suspension using a filter
8.1: A solution is a type of mixtureSlide10
Solvent and solute particles interactThe parts of a solution are not changed into new substances The solute and the solvent can still be physically separated, though they do interactEx: a solid dissolves in a liquid, the particles of the solute are surrounded by particles of the liquid (solvent)
The solute particles become evenly distributed through the solvent
8.1: A solution is a type of mixtureSlide11
Solvent and solute particles interact (2)The way a solid compound dissolves in a liquid depends on the type of bonds in the compoundIonic compounds split apart into individual ions
Ex: table salt dissolves in water – the sodium and chloride ions separate, and each ion is surrounded by water molecules
Covalent compounds dissolved in water, the molecules stay together and are surrounded by solvent molecules
Ex: table sugar dissolves in water – C12H22O11 stays as such
8.1: A solution is a type of mixtureSlide12
Properties of solvents change in solutionsSolutes change the physical properties of a solvent in every solutionA solution’s physical properties differ from the physical properties of the pure solventDependent on the amount of solute addedSlide13
Lowering the Freezing PointFreezing Point: temperature Liquid SolidA solvent’s freezing point is lowered when a solute is dissolved in it
Ex: add salt to water – freezing point drops below
32
o
F (
0oC)Useful for snow and ice on sidewalks and roads (water freezes at a lower temperature, can help to melt ice)A limit: can get down to
-6oF (-21oC) before the melted ice will freeze again
Ice cream maker:Canister surrounding ingredients holds a mixture of salt and iceThe lower freezing point causes the ice to melt, absorbing heat from surroundings
This includes the ice cream ingredients, which get chilledThen tiny ice crystals form all at once in the ice cream mixture rather than a few crystals growing larger over time (as would happen in a regular freezer)Slide14
Raising the Boiling PointBoiling Point: temperature liquid gas Boiling point of a solution is higher than the boiling point of the pure solvent
Solution can remain a liquid at a higher temperature than its pure solvent
Ex: boiling point of water = 212
o
F (100
oC)Salt raises the boiling point of waterDependent on amount of salt addedSummary: a solute lowers the freezing point and raises the boiling point of the solvent in the solution
Extends the temperature range in which the solvent remains a liquidUses: antifreeze in a car’s radiator (ethylene glycol added to water)Prevents the water from freezing in the winter
Keeps it from boiling in the summer Slide15
s