C3- Chemical Equations

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  • Created by: Janviixo
  • Created on: 15-02-16 16:40
What is an exothermic reaction? Give an example.
it gives out energy to the surroundings- burning fuels
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What is an endothermic reaction? Give an example.
it takes in energy from the surroundings- thermal decomposition
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What reaction is needed to break bonds?
endothermic reaction
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What reaction is needed to make bonds?
exothermic reaction
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Define specific heat capacity
the amount of energy needs to raise the temperature of 1g of water by 1 C
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What is the formula for energy transferred?
Energy transferred= mass x specific heat capacity x temp change
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What is the formula for energy given out per gram?
energy given out = energy released / mass of fuel burned
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What is the calorimetric method?
burning a spirit burner to heat water
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Give an example of a slow reaction
rusting of iron or chemical weathering
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Give an example of a moderate reaction
reacting magnesium with a dilute acid
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Give an example of a fast reaction
an explosion
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Name 2 ways you can measure how quickly gas is produced?
1) Measure change in mass- balance 2) Measure volume of gas given off- gas syringe, regular intervals
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What 2 things does the rate of reaction depend on?
1) collision frequency of particles 2) energy transferred during a collision
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What is the limiting reactant?
The reactant that is totally used up
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Name 4 things that increase the number of collisions
1) Increasing temperature- more energy 2) Increasing concentration/ pressure 3) Smaller solid particle- high surface area 4) Catalyst- increase no. of successful collisions
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How does a catalyst increase the number of successful collisions?
Gives reacting particles a surface to stick to where they can bump into each other- reduces energy needed
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What is the difference between relative atomic mass and relative formula mass?
Ar: mass number of an element Mr: atomic masses in a compound added together
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What is meant by 'mass is always conserved' in a chemical reaction?
no mass is lost or gained
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What 3 steps should you use when calculating mass?
1) Write out balanced equation 2) Work out Mr for bits you want 3) Divide to get 1, then multiply to get all
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What is the formula for atom economy?
atom economy = total Mr of desired / total Mr of total (x 100%)
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What is a disadvantage of a low atom economy?
uses up resources very quickly, makes lots of waste products that have to be disposed
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What is the formula for percentage yield?
% yield = actual yield/ predicted yield (x 100%)
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Why do industrialists want a high percentage yield as possible?
to reduce waste and costs
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Name 4 ways why you never get 100% yield
1) Evaporation 2) Not all reactants react- reversible reactions 3) Filtration 4) Transferring liquids- some left on inside surface
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What is batch production? Give an example
it only operates at certain times- pharmaceutical drugs
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Name an advantage and disadvantage of batch prodcution
Adv- start up cost relatively low Disadv- labour intensive
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What is continuous production? Give an example
it runs all the time- large scale industrial manufacture of popular chemicals, haber process
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Name an advantage and disadvantage of continuous production
Adv- runs automatically Disadv- big start up costs
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What are the 3 stages a pharmaceutical drug has to go through?
Research and development, trialling and manufacture
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What happens during the trial stage of a drug?
has to go through animal and human trials until the manufacture proves that it meets legal requirements
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Explain how a substance is extracted from a plant
the plant has to be crushed, then boiled and dissolved in a suitable solvent.The substance is then extracted by chromatography
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Name 2 ways you can test for purity?
1) Chromatography- won't separate 2) Melting/Boiling points- impure substance will be too high/low than normal
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Define allotropes
different structural forms of the same element in the same physical state
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Name 4 properties a diamond has
each atom has 4 covalent bonds, very rigid and hard-ideal for cutting tools. high melting point, doesn't conduct electricity as there's no free electrons
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Describe 2 uses of graphite
lead in pencil and lubricating material- layers weakly held together .:. slippery and can be rubbed onto material
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Why can graphite conduct electricity?
only 3 of carbon's 4 outer electrons used in bonds .:. there are lots of delocalised electrons that can move
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What can be joined together to form nanotubes?
fullerenes
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Give 2 uses of nanotubes
industrial catalysts and tennis rackets
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Other cards in this set

Card 2

Front

What is an endothermic reaction? Give an example.

Back

it takes in energy from the surroundings- thermal decomposition

Card 3

Front

What reaction is needed to break bonds?

Back

Preview of the front of card 3

Card 4

Front

What reaction is needed to make bonds?

Back

Preview of the front of card 4

Card 5

Front

Define specific heat capacity

Back

Preview of the front of card 5
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