Chemistry-(GCSE) Summer Term (Yr.10)

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what is electrolysis ?
chemical decomposition produced by passing an electric current through a liquid or solution containing ions
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what is the cation ?
a particle with positive charge, formed when one or more electrons are lost
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what is an anion ?
a particle with a negative charge, formed when one or more electrons are gained
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what is the electrode ?
an electrical conductor which is submerged in the electrolyte during electrolysis
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what is an electrolyte ?
a liquid or solution used in electrolysis to conduct electricity between the two electrons
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draw an electrolysis diagram:
book 2 `
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what happens to energy in chemical reactions ?
its conserved and stays the same
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what is an exothermic reaction ?
a reaction which transfers energy to the surroundings so the temperature of the surroundings increases
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what is an endothermic reaction ?
a reaction which takes energy from the surroundings so the temperature of the surroundings decrease
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what makes a chemical reaction take place ?
collisions with other particles and sufficient energy- collision theory
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what is a reaction profile ?
draw book 2:
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what type of reaction breaks bonds, forms bonds ?
breaks- endothermic, forms exothermic
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what is activation energy ?
the minimum amount of energy needed to make particles react
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define cell
a system which contains chemicals which react and produce electricity, it contains 2 different electrodes in contact with an electrolyte
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how is the electricity produced in a cell ?
the chemical reactions involved set up a charge difference between the electrode and if connected with a wire the charge flows and electricity is produced
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how can we change voltage ?
by changing the metals because different metals react differently with the same electrolyte, have two metals with the biggest difference in reactivity, have a highly concentrated electrolyte
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what is a battery ?
two or more cells which are connected in series, the voltage produced is equal to the sum of each cells separate voltage
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how do re- chargeable batteries work ?
because the chemical reaction inside the cell is reversed when an external electrical current is supplied
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what 4 factors increase the rate of reaction ?
temperature, surface area, concentration/ pressure, catalyst
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what is the collision theory ?
the rate of reaction depends on two things, collision frequency and energy transferred during a collision
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how does temperature increase the rate of reaction ?
the particles move quicker which causes more collisions
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how does concentration/ pressure increase the rate of reaction ?
more concentrations means more collisions with particles, more pressure means more particles are squashed up together so there's more collisions
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how does surface area increase the rate of reaction ?
bigger the surface area, all together, more collisions with the substance and water particles
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how can rates of reactions be measured ?
increase in product or decrease in reactant divided by time taken
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how do you measure the rate of a precipitate (solid) reaction ?
by noting teh change in mass or collect the volume of gas which has been given off with a syringe
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how can graphs be used to calculate the rate of reaction ?
by using the gradient change in y divided in change in x
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what is a fuel cell ?
an electrical cell that's supplied with fuel and oxygen and efficiently transfers the energy released by the reaction between them as electricity
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when do fuel cells produce a continous voltage ?
all the time that they are supplied with a consistent supply of a suitable fuel and oxygen
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what are the pros and cons of an alkaline cell ?
pro- cheaper to make, con- ends up in landfill, expensive to recycle.
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what are the pros and cons of a rechargeable cell ?
pros- reduce resources used, can be recharged, cons- costs more to be made and bought
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what are the pros and cons of a hydrogen cell ?
pros- easy to maintain as no moving parts, only water produced, cons- v.expensive to make constant supply of hydrogen needed which a flammable gas
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draw a hydrogen cell diagram
book 2
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define reversable reaction
a reaction where the products of the reaction can themselves react to produce the original reactants
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define equilibrium
when the amount of reactants and products reach a balance
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what is le chateliers principle ?
if a factor affecting the position of an equilibrium is alterted the position of the equilibrium shifts to oppose the effect of the change, its used to determine what effect a change will have on a mixture at equilibrium
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how does the change in concentration affect equilibrium ?
if concentration of substance a increases equilibrium goes to the right and if substance a decreases equilibrium shifts to the left
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how does the change in pressure affect equilibrium ?
increase in pressure favours side with fewer moles, decrease in pressure favours side with more moles
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how does the change in temperature affect equilibrium ?
increased endothermic reaction is favoured, decreased exothermic reaction is favoured, adding a catalyst has no affect
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what side will the reaction favour if temperature decreases ?
the exothermic route because it gives out thermal energy
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what side will the reaction favour if temperature increases ?
the endothermic way because the thermal energy is taken in
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Other cards in this set

Card 2

Front

what is the cation ?

Back

a particle with positive charge, formed when one or more electrons are lost

Card 3

Front

what is an anion ?

Back

Preview of the front of card 3

Card 4

Front

what is the electrode ?

Back

Preview of the front of card 4

Card 5

Front

what is an electrolyte ?

Back

Preview of the front of card 5
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