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What is energy?
• You may sometimes feel like you are having too much work and not enough energy to do the work!
Energy is the Capacity to do work or to produce change.– Homework induces a change in your brain:
connections between neurons are formed, therefore it requires energy.
100 g
100 gOne Joule represents the energy needed to lift an object weighing one Newton (N) to the height of one meter (m).
1 Joule
1 meter
Unit of energy:
The standard unit of energy is the ___________Joule (J) .
On earth 1N = 100 g
100 g
100 g
✓
Thermal energy• The energy, that is contained in the agitation
of the molecules.• The amount of thermal energy, that a
substance contains, depends on the degree of agitation of its molecules (temperature)…
• … and on how much substance there is.
Which contains more thermal energy?80°C 50°C
• Melting of snow.
• Lifting of a hot air balloon by heating the air.
Examples of work or change induced by thermal energy.
Electromagnetic waves: transport energy from one place to another.
• The amount of transported energy depends on the wavelength and the quantity of radiation.
• The shorter the wavelength of a given number of waves the more energy the wave can transport.
Radiant Energy
Examples of work or change induced by radiant energy.
• Food is heated by microwaves
• Getting suntanned or burned from ultraviolet rays
Mechanical energy
• .. Is the energy that results from the _____of an object, its _____, and its _____________ _____________.
speedmass relationship to
its surrounding
Mechanical energy
• .. Is the energy that results from the _____of an object, its _____, and its _____________ _____________.
> The greater the speed the greater the mechanical energy.
> The greater the mass the greater the mechanical energy.
> The higher the object the greater its mechanical energy.
speedmass relationship to
its surrounding
• Crater caused by an asteroid.
• Electricity generated by spinning a turbine (hydro + wind).
• Dent in a car from a crash.
Examples of work or change induced by mechanical energy.
Chemical Energy
• … is the energy stored in the bonds of a molecule
• Energy is stored when bonds are formed …• … and can only be released when bonds are
broken and reorganized.
Chemical Energy
• … is the energy stored in the bonds of a molecule
• Energy is stored when bonds are formed …• … and can only be released when bonds are
broken and reorganized.• The amount of energy stored in a molecule
depends on the strength and the number of bonds.
• COMBUSTION of gasoline Driving of a car.
• PHOTOSYNTHESIS: light energy chemical energy
• CELLULAR RESPIRATION: chemical energy animals grow move and think.
Examples of work or change associated with chemical energy.
Energy Form Energy Source
Solar Energy Sun
Electrical Energy Power Station
Wind Energy Wind
Sound Energy Sound Waves
Hydraulic Energy Moving Water
Nuclear Energy Nucleus of an atom
Other Forms of Energy
HEAT is the transfer of thermal energy from one place to another.
• The molecules in the drink transfer thermal energy to the cup the cup gets warm.
• The molecules of the cup transmit vibration energy to the molecules of our skin.
• Agitation of the molecules in our skin feels warm to us.
Heat / Heat transfer
Energy
Transformation of energy
• The transformation of energy is the change of one form of energy into another.
light chemical
chemical chemical mechanicalmechanical
electrical thermal
• Matter• Pure Substance• Compound • Element• Molecule• Particle• Characteristic Chemical
Property• Characteristic Physical
Property
• Mixture• Heterogeneous• Homogeneous• Colloid• Solution• Solute • Solvent• Solubility• Concentration• Dilution
Terms to Know
• Matter is made up of particles that are in constant motion.
• Particles in a solid are very close together and move very little.
• Particles in a liquid are close together and move more than the particles in a solid but less than particles in a gas
• Particles in a gas are very far apart and move a lot.
Particle Model
MIXTURES
heterogeneous homogeneous
Suspension
?✗
ColloidSolution
PURE SUBSTANCES
compounds elements
MATTER
Contain only one type of particle
• Decantation• Centrifugation• Filtration• Evaporation• Distillation• Chromatography
Separation Techniques
• Melting Point• Boiling Point• Density• Solubility
• Do not change the substance during the identification process.
Characteristic physical properties
Chemical characteristic propertiesGas Liqid Certain metal
saltsHydrogenBurning splint test explosion
WaterCobalt chloride paper turns pink
Flame test Flame will take a characteristic colour depending on the metal
OxygenGlowing splint test re-ignition
Acid /BaseLitmus paper acid > red base > blue
Carbon dioxideLimewater test gets cloudy
a) Decantationb) Filtrationc) Centrifugationd) Distillation
Which purification technique would be least useful in separating a mixture of two liquids?
Property Results
Boiling Point 65°C
Mass 79g
Volume 100mL
Colour Clear
Reaction to litmus paper No change
Which of the properties in the table below can help us identify the unknown substance tested?
Identify the Unknown using Apendix 1 in your textbook p.
418-423