C6

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what is electrolysis?
a chemical reaction in which an ionic liquid is broken down into its element using an electronic current
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what happens at the anode?
positive ions move to the anode to gain electrons
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what happens at the cathode?
negative ions move to the cathode to lose electrons
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what can increase the amount of product made at the electrode?
a larger current flow and/or a longer amount of time
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how do you calculate the amount of electricity produced?
quantity of electricity (coulombs) = current (amps) x time (seconds)
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what happens at each of the electrodes in the electrolysis of copper sulfate?
at the anode: ions lose their electrons so become neutralized atoms of oxygen gas - therefore the mass decreases. at the cathode the ions gain electrons to become neutralized atoms of copper so the mass increases as the atoms stick to the cathode
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what is the equation for the electrolysis of sodium hydroxide, potassium nitrate and sulfuric acid?
(at the cathode) 2H+ + 2e- = H2 (at the anode) 4OH- - 4e- = O2 + H2O
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what is an exothermic reaction?
a reaction that releases engery
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what is an endothermic reaction?
a reaction that takes in energy
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what kind of reaction occurs between hydrogen and oxygen and what is the equation?
an exothermic reaction, 2H2 +O2 = 2H2O
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what is a fuel cell?
an electrochemical cell that converts chemical energy into electricity
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what can fuel cells be used for?
for creating energy in spacecraft as the water made is pollution-free so can used as drinking water for the crew
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name three advantages of using fuel cells?
produce less pollution, very efficient, transfer energy directly, have few stages and are simple to construct, lightweight and compact, no moving parts
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what are the disadvantages of using fuels cells?
often contain poisonous catalysts which have to be carefully disposed of and to get hydrogen may come from burning fossil fules
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what is rust?
hydrated iron oxide
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when does rust form?
when iron reacts with both oxygen and water
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what kind of reaction is this?
redox reaction, that contains both oxidation and reduction
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what is oxidation and reduction?
oxidation is the gain of oxygen and reduction is the removal of oxygen
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what are some ways of preventing rust from occurring?
coating to iron in oil, grease or paint
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why does this help?
stops the water and air getting to the metal
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what are some other ways of preventing rust?
galvanising-coating the iron with zinc, alloying, tin painting, sacrificial protection-placing a more reactive metal in contact with the iron
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what is a displacement reaction?
a more reactive metal will displace a less reactive metal in a reaction
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give an example of a displacement reaction
magnesium is more reactive than zinc, which is more reactive than iron, which is more reactive than tin - magnesium + zinc chloride = zinc + magnesium chloride
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what are alcohols made of?
hydrogen, carbon and oxygen
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what are some uses of ethanol?
making alcoholic drinks, making solvents such as methylated spirits, fuels for cars
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what is the general formula for alcohol?
CnH(2n+1)OH
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ethanol can be made through fermentation. yeast is used to ferment glucose solution, what is the word equation?
glucose = ethanol +carbon dioxide
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what is the symbol equation for fermentation of glucose?
C6H12O6 = 2C2H5OH
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the fermentation mixture has to be kept between what temperature for a few days?
25C* - 50C*
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why does it have to be kept at this temperature?
if it falls below the yeast becomes inactive, if it rises above, the enzymes in the yeast denature and stop working
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the chemical reaction to turn ethene to ethanol is reversible, how?
through hydration and dehydration
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ethene can be hydrated to make ethanol by doing what?
passing it over a heated phosphoric acid catalyst and steam
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what is the word and symbol equation for this process?
ethene + water = (phosphoric acid catalyst) = ethanol, C2H4 + H2O = C2H5OH
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why is ethanol made by hydration non-renewable?
the ethene was made by cracking components in crude oil
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give some details about the hydration of ethene
quick to make, available in large quantities in this country, it is a continuous process
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give some details about the fermentation of ethene?
slow batch process, uses a lot of energy and is expensive, has a higher percentage yield than hydration
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what is the ozone made out of?
O3
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what are chlorofluorocarbons made up of?
chlorine, fluorine and carbon
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what are they used for?
refrigerators and aerosols
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what are some properties of CFCs?
they have a low boiling point, insoluble in water and are very unreactive
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what is an alternative for CFCs?
HFCs, hydrofluorocarbons
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depletion of the ozone layer causes harmful UV light to enter the earths atmosphere. what can this cause?
ageing of the skin and sunburn, skin cancer and risk of cataracts
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when a CFC molecule is hit by an unltraviolet light a chlorine atom called a radical(*) is made. what is the equation for this?
R-Cl = (UV light) = R* + Cl*
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when the chlorine radical reacts with an ozone layer molecule what is made?
a chlorine monoxide radical molecule and an oxygen molecule
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what is the equation for this?
Cl* + O3 = ClO* + O2
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the chlorine monoxide radical molecule then reacts with an oxygen atom to produce what?
a chlorine radical and an oxygen molecule
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what is the equation for this?
Cl* + O* = Cl* + O2
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how does soap lather with hard and soft water?
hard water= doesn't lather well, soft water= does lather well
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what is hardness in water caused by?
calcium and magnesium ions from dissolved salts
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what are the two hardness's in water?
temporary and permanent
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what is temporary hardness?
forms when rainwater comes into contact wiht rock that contains calcium carbonate. it can be removed by boiling
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what is permanent hardness?
caused by dissolved substances like calcium sulfate. it cannot by removed by boiling
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what is the equation for temporary hardness?
calcium carbonate + water + carbon dioxide = calcium hydrogencarbonate
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what is the word equation for the removal of temporary hardness?
calcium hydrogencarbonate = calcium carbonate + water + carbon dioxide
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what is the symbol equation for removing temporary hardness?
Ca(HCO3)2 = CaCO3 + H"O + CO2
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what dies insoluble calcium carbonate deposit on kettles?
limescale
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Other cards in this set

Card 2

Front

what happens at the anode?

Back

positive ions move to the anode to gain electrons

Card 3

Front

what happens at the cathode?

Back

Preview of the front of card 3

Card 4

Front

what can increase the amount of product made at the electrode?

Back

Preview of the front of card 4

Card 5

Front

how do you calculate the amount of electricity produced?

Back

Preview of the front of card 5
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