physical and chemical change physical change –the altering of the physical form but not...
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Physical and chemical change
• Physical change– the altering of the physical form but not
composition of matter– ex. Pounding, pulling, changes of state
• Knowledge of physical change leads to…– the understanding of separation of mixtures
– ex. Distillation, crystallization, chromatography, filtration
Chemical change
• Chemical change– change in which the matter is converted into
matter with different composition and properties
Indicators of chemical change
1. heat and/or light energy– Energy changes within the system
2. Production of gas
- release of gas from the system
3. Formation of a precipitate
- when two (or more) solutions are put together an insoluble solid is produced
4. Color change
- the system changes color
- not always an indicator of chemical change (can be physical
MIXTURES
mixture: - combination of two or more kinds
of matter each of which retains its own composition and properties
- physical blend of two or more substances
heterogeneous mixture: - a mixture containing substances that are not evenly distributed
- different from point to pointex. granite ---> quartz, feldspar, and mica
More of Mixtures:
Phase
• mixtures that are obviously heterogeneous and have separate, distinct parts
Ex. Oil forming layers in water is another
Interface – the region where two or more phases meet
M o M
homogeneous mixture - a mixture containing substances that are
uniformly distributed with the particles blended completely
- composition and properties are uniform throughout
- also called solutions (mixed on a scale of individual particles) ex. I molar copper II sulfate
• To the eye, the mixture appears to be pure substance.
SolutionsSolutions(Homogeneous Mixtures)(Homogeneous Mixtures)
Can you tell the difference?Can you tell the difference?
Parts of a Solution• SOLUTE – the part of
a solution that is being dissolved (usually the lesser amount)
• SOLVENT – the part of a solution that dissolves the solute (usually the greater amount)
• Solute + Solvent = Solution
Solute Solvent Example
solid solid Brass: Copper and Zinc
solid liquid Seawater: NaCL in water
gas solid Moth balls: naphthalene
liquid liquid Ethyl alcohol and water (miscible)
gas liquid SODA: CO2 gas in water
gas gas AIR: O2 gas, N2 gas
DO NOT NEED TO COPY CHART
DefinitionsDefinitions
Solutions can be classified as Solutions can be classified as saturatedsaturated or or ununsaturatedsaturated..
A A saturatedsaturated solution contains the solution contains the maximum quantity of solute maximum quantity of solute that dissolves at that that dissolves at that temperature.temperature.
An An unsaturatedunsaturated solution contains solution contains less than the maximum less than the maximum amount of solute that can amount of solute that can dissolve at a particular dissolve at a particular temperaturetemperature
DefinitionsDefinitionsSUPERSATURATED SOLUTIONSSUPERSATURATED SOLUTIONS contain more solute contain more solute
than is possible to be dissolved in a given amount of than is possible to be dissolved in a given amount of solventsolvent
Supersaturated solutions are unstable. Supersaturated solutions are unstable.
-- the supersaturation is only temporary-- the supersaturation is only temporary
-- need to warm the solvent so that it will dissolve -- need to warm the solvent so that it will dissolve moremore
-- then need to cool the solution slowly-- then need to cool the solution slowly
Separation of Mixturestypes of…
• Filtration– Separation of mixture on the basis of
differences in the size of the particles– Mostly used to separate solids from liquids (but
filtration is used to separate all phases of matter from one another)
Ex. Air filters separate gas (air) from solid (dirt particles)
• Distillation– Based on the tendency of a substance to
vaporize (turn to a gas)– Based on boiling point differences– The substance in the mixture with the lowest
boiling point will vaporize first from the mixture
Ex. Crude oil
• Crystallization– Separation of the mixture is based on
solubility differences– Temperature changes within the mixtures
change solubility of parts of the mixture
Solubility – the amount of a solute that is able to dissolve in a given amount of solvent
Ex. Rock candy
• Chromatography– Based on the differences in solubility– Two types Gas and Paper– Mixture separates as it travels (most soluble
separates first)
Solute – substance that gets dissolved
Solvent – substance that does the dissolving
Ex. Separating ink in a marker
Concentration: • amount of solute in a given amount of solvent (can be determined quantitatively)
Dilute: • a solution with a small amount of solute per solvent amount (relative term)
Concentrated: • a solution with a large amount of solute per solvent amount (relative term)
BOTH DILUTE AND CONCENTRATED ARE QUALITATIVE
SOLUTION CHEMISTRY
Concentration of SoluteConcentration of SoluteConcentration of SoluteConcentration of Solute
The amount of solute in a solution is The amount of solute in a solution is
given by its given by its concentrationconcentration.
Molarity (M) = moles soluteliters of solution
The concentration of a solution is said to be its molarity.
Ex. 1 M CuSO4
“1 molar copper II sulfate