454568
Description
Mind Map by iamawesomelyepic, updated more than 1 year ago
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Created by iamawesomelyepic
almost 11 years ago
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ENERGY
CHANGES
- EXOTHERMIC
- products have lower energy than
reactants
- measured in kilojoules
- EG : neutralisation of an acid by
alkali, combustion of fuels,
reaction between iron & sulfur
- energy given out
- rise in temperature
- products have lower energy than
reactants
- ENDOTHERMIC
- energy taken in
- fall in temperature
- product have HIGHER energy than
reactants
- measured in kilojoules
- EG: thermal decompostion of Calcium
Carbonate, photosynthesis, reaction that
take place during cooking
- energy taken in
- MORE ON ENERGY
CHANGES
- In chemical reaction, bonds are broken,
bonds are formed
- Energy TAKEN IN for breaking
bond (ENDOTHERMIC)
- Energy RELEASED when bonds form
(EXOTHERMIC)
- energy taken in > energy
given out = endothermic
- energy taken in < energy
given out = exothermic
- amount of energy needed to break bonds is
DIFFERENT from amount of energy given out by
forming bonds
- In chemical reaction, bonds are broken,
bonds are formed
- CALCULATING ENERGY
CHANGE
- use balanced equation
- energy change = energy in - energy out
- (-) shows EXOTHERMIC
- (+) shows ENDOTHERMIC
- use balanced equation
- ENERGY FROM
FUELS
- Substance we use as source of
energy
- FOSSIL FUELS
- oil, natural gas, coal
- burns oxygen in the air
- Chemical energy is released as heat
- in homes : cooking & heating
- gas-fired power stations : boil water to
make steam which generates electricity
- combustion produces carbon dioxide = global warming
- oil, natural gas, coal
- NUCLEAR FUELS
- Radioisotopes
- not burned, broken down by bombarding them with neutrons
- Atomic energy released as heat
- nuclear power stations : boils water to make steam which generates
electricity
- Harmful radiation
- products are radioactive
- Radioisotopes
- Substance we use as source of
energy
- CELLS
- SIMPLE CELLS
- consists of rods of two different metals (one metal gives up
electrons more readily than the other) standing in an
electrolyte
- REDOX reactions provide a current
- consists of rods of two different metals (one metal gives up
electrons more readily than the other) standing in an
electrolyte
- FUEL CELLS
- hydrogen reacts with oxygen without combustion
- at (-)pole :hydrogen is oxidised
- at (+)pole: oxygen is reduced
- used to provide electricity in spacecrafts
- clean form of energy
- used in some homes for electricity
- being developed for transportation
- hydrogen reacts with oxygen without combustion
- SIMPLE CELLS
- REVERSIBLE
REACTIONS
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