c hemical and p hysical r eactions. p hysical p roperties a characteristic of matter that can be...
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CHEMICAL AND PHYSICAL
REACTIONS
PHYSICAL PROPERTIES A characteristic of matter that can be
observed without changing the substance into another substance
Examples: Freezing Boiling Melting Hardness Color Shine flexibility Solubility
CHEMICAL PROPERTIES Characteristics of a substance that describe
its ability to change into a new substance
Examples: Burning Rusting Tarnishing
Changing into a new substance requires another chemical, like O2 changing to CO2
PHYSICAL AND CHEMICAL PROPERTIES ACTIVITY Using the objects provided, list the physical
and chemical properties of each object
Create a table to classify each object based on its properties
Use the equipment & substances available
A: Salt B: Crayon C: Antacid
Physical or chemical?
Reacts with water
Yes or no?
Does not react
Soluble
Not soluble
Hard
Soft
Color
Reacts with vinegar
Does not react with vinegar
Physical Properties or Chemical PropertiesMetallic, non-metallic, magnetic, heat
conductor
PHYSICAL AND CHEMICAL PROPERTIES ACTIVITY 2 Using the substance provided, investigate
and report on its chemical and physical properties
Use your Lab Book, create a table with Physical and Chemical Properties noted
PHYSICAL CHANGES The form or appearance of a substance is
altered, without combining it with another substance
Examples?
Ice to water to steam Ice cream melts Make Kool-aid Cut paper
Reversible!!!
CHEMICAL CHANGES A change in matter that results in one or
more new substances
Chemical in the original substance combines with another chemical to create a new substance
Examples? Burning anything Baking cookies Fireworks
Not reversible!!!
EVIDENCE OF CHEMICAL REACTIONS Color change
Heat given off/absorbed
Change in odor
Gas released
Light given off
Precipitate
CHANGES IN ENERGY Is energy released/taken in during a physical
or chemical change?
Energy can be light, heat, or sound
If heat energy is removed during a reaction, it is an exothermic reaction (feels hot)
If energy is added during a reaction, it is an endothermic reaction (feels cold)
COMMON CHEMICAL REACTIONS Photosynthesis
CO2 + H2O = C6 H12 O6 + O2
Respiration O2+ H2O = CO2 + H2O
Combustion
Rusting
MINI-LAB! Determine whether each reaction is
endothermic or exothermic
Make hypotheses for each of the following: Strike a match Vinegar and antacid
Write 3 observations for each
Write a one sentence conclusion for each
RATES OF CHEMICAL REACTIONS How quickly a chemical reaction can
take place
Controlled by 4 thingsSurface AreaTemperatureConcentrationSubstances
CatalystsInhibitors
REACTANTS AND PRODUCTS Reactants are combined together to create
products
What are the reactants and products in the following equations? C + 2 O CO2
2 H + O H2O
What do you notice about these equations? There are the same number of atoms on the left as
on the right Coefficients, subscripts
CHEMICAL EQUATIONS Label the chemical equation below:
CaCO3 CaO + CO2
TYPES OF REACTIONS Synthesis
Start with 2 or more elements or compounds and combine them to make something more complex
Decomposition Start with 1 compound and break it down to form
2 or more elements or compounds
Replacement Elements trade places in a reaction
CONSERVATION OF MASS You must end up with the same amount you
started with
Mass cannot be created or destroyed
WARM-UP-ON YOUR OWN PAPERWRITE WHETHER EACH REACTION IS SYNTHESIS, DECOMPOSITION, OR REPLACEMENTMg + O2 MgO2H2O2 2 H2O + O2
2Cu2O + C 4Cu + CO2
FeS + 2HCl FeCl2 + H2SP4O10 + 6H2O 4H3PO4
Fe2O3 + C Fe + CO2
SO2 + O2 SO3
BALANCING EQUATIONS Goal- Have the same number of atoms on
both sides of the equation.
Rules Coefficients multiply You can not change subscripts If there is no subscript after an atom, then you
know there is only 1 atom present
Examples on board Practice worksheet