Chemistry - Everything C6 for OCR Gateway exam!

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What is a Redox Reaction
When electrons are lost or gain (OIL RIG)
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What is used as an oxidising agent in the oxidisation of Iron (II) Salt?
Chlorine gas
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What do Iron atoms oxidise into when reacting with dilute acid?
Iron (II) Ions
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What happens in a displacement reaction?
The more reactive metal will displace (Kick out) the less reactive metal in a compound
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Is it the metal Ion or atom that is reduced during a displacement reaction?
Metal Ion
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Is the rusting of Iron Oxidation or Reduction?
Oxidation - because each Fe atom loses three electrons (though oxgen is reduced as it gains two electrons)
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What is stainless steel made up of?
Carbon and chronium
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What are four ways of preventing rust?
-Using alloys -Painting, oiling or greasing -Coating in tin -Galvanising(coat of zinc is put aroun iron, is more reactive, so zinc loses electrons in preference) or bolting on magnesium, for same reason
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Where will the positive ions in an electrolysis reaction go and why?
Pure Cathode (Negative electrode) to gain electrons
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Where will the negative ions in an electrolysis reaction go and why?
Impure Anode (positive electrode) to lose electrons
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What happens to ions as they lose of gain electrons?
They become atons or molecules and are discharged from the solution at the electrodes
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Where do the ions come from for aqueous solutions in electrolysis?
The dissolved substance and the water
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What can Copper (III) sulfate be electrolysed into?
Copper and Oxygen
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What is the reaction at the cathode for the electrolysis of Copper (III) Sulfate?
Cu2+ +== 2e- = Cu
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What is the reaction at the anode for the electrolysis of Copper (III) Sulfate?
4OH- - 4e- = O^2 + 2H^2O
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What happens at the cathode during this reaction?
Starts as Carbon and gets coated in a layer of copper
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What happens at the anode during this reaction?
Hydroxide ions are discharged from the solution and concerted into oxygen and water
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Why can't an Ionic solid be electrolysed?
The ions are in fixed positions so can't move
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Are positive metal ions reduced or oxidised at the cathode?
Reduced
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Are negative metal ions reduced or oxidised at the anode?
Oxidised
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What is the product at the anode and cathode for the electrolysis of lead iodide?
Cathode - lead Anode - Iodine
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What are the products at the anode and cathode for the electrolysis of Potassium Chloride?
Cathode - Potassium Anode - Chlorine
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What happens you increase the amount of electrons in an electrolysis reaction?
The amount of substance produced is increased
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How can you increase the amount of electrons in a electrolysis reaction?
Electrolyse for a longer time or Increasing Current
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What is the amount of charge in a current equal to?
Current X time in secs
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What do Fuel Cells do?
Use Hydrogen and oxygen to react to produce electrical energy (that is efficient) and water
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In a Hydrogen-Oxygen Fuel Cell, what is at the anode and what it at the cathode?
Anode - Hydrogen Cathode - Oxygen
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What happens at the cathode of this reaction?
Oxygen gains electrons and reacts with warer to make OH- ions
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What happens at the anode of this reactions?
Hydrogen combines with hydroxide ions to produce water and electrons (Hydrogen loses electrons)
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What is the equation for the reaction of Hydrogen and Oxygen in a Fuel Cell
Hydrogen + Oxygen = Water 2H^2 + O^2 = 2H^2O
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What are the advantages of Fuel Cells? (5 things)
- More efficient than power stations -Direct energy transfer (as electricity is directly generated from reactions) - Few stages of reaction so less energy lost -No moving parts (no energy loss through friction) -No pollution
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What are the disadvantages of Fuel Cells? (2 Things)
- Fuel Cell needs a lot of energy to be powered (which may come from burning fossil fuels, so pollution) - Contain Poisonous catalyst that is expensive to dispose of and may cause environmental problems
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What are the advantages of using Fuel Cells in space craft? (5 things)
-Hydrogen and Oxygen is reasily available from rocket fuel tanks - Light Weight and compact (so don't take up space) - No moving parts, so less likely to break - Makes water, can be used as drink - No waste products or pollutants
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Where can Hydrogen be obtained from?
Decomposing water
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What are CFC's made up of?
Carbon, Chlorine and Flourine
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What are some positive properties of CFC's
Non-Toxic, non- flammable, insoluble in water, unreactive, low boiling points
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What is the ozone layer made of and what does it do?
Made of O^3 (oxygen three) and absorbs UV rays and breaks then into an oxygen molecule and atom ( UV light + O^3 = O + O^2)
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What is a free radical?
Where a covalent bond breaks and the electrons are shared out between atoms, meaning it is unpaired
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Are free radicals reactive? Why/why not?
Yes - They have an unpaired electron that easily reacts
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What does UV light do to carbon-chlorine bonds in CFC's?
Breaks down the carbon-Chlorine bonds to form free radicals
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Whatdo the Chlorine free radicals (from the previous reaction) do to the ozone?
They react with the ozone to turn it into oxygen and chlorine oxide
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From the previous reaction, what does the chlorine oxide react with and what does it create?
Reacts with Ozone to create two oxygen molecules and another Chlorine free radical
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What does the new Chlorine free radical them do?
Reacts with another ozone molecule, and repeats the cycle
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What are two alternatives to CFC's and why?
Alkenes - don't react with ozone Hydroflourocarbons (HFC's) don't contain chlorine
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What does hard water form?
Limescale
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What is not formed when soap is mixed with hard water?
A lather
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What is Hard Water made of?
Calcium Ions and Magnesium Ions
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What is the equation for the reaction of hard water?
Carbon dioxide + water + calcium carbonate = calcium hydrogencarbonate
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What causes temporary hardness?
hydrogencarbonate ion in Calcium
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What causes hardness?
Dissolved calcium sulfate
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How can temporary hardness be removed?
By Boiling (the hydrogencarbonate decomposes)
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How can both types of hardness be removed? (2 ways)
Adding Sodium Carbonate (washing soda) Ion Exchange resin (contains lots of sodium ions and exchanges them for calcium or magnesium)
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What type of water contains the least amount of hardness?
Distilled
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What does fermentation do in the process of making alchohol?
Converts sugars into ethanol through use of enzymes found in yeast
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What are the two ways to make pure alchohol?
Fractional distillation of fermented ethanal - Hydrating ethene (ethene reacts with steam to make ethanol)
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What are the conditions needed for the reaction of Hydrating Ethene?
Temp = 300'c Pressure = 70 atmospheres Heated Phosphoric acid catalyst
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Compare the maufature of fermentation compared to hydration
Fermentation = batch process, so slow and inefficient. Hydration = continuous process, so made quicker, but more expensive process due to conditions needed
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Comparte the sustainability of fermentation compared to hydration
Fermentation = renewable Hydration = non-renewable
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Compare the purity of fermentation compared to hydration
Fermentation - Impure and has to be purified Hydration - High Purity
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Compare the atom economy and % Yield of fermentation compared to hydration
Fermentation - low atom economy and % Yield Hydration - high atom economy, low initial % Yield, but recycling unused products means high
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What is an example of an oil-in-water emulsion?
Milk
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What is an example of a water-in-oil emulsion?
Butter
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What is the equation for saponification and what does it make?
Fat + sodium hydroxide = Soap + glycerol -Makes soap
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How many C=C bonds do monounsaturated fats contain?
One
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How many C=C bonds do Polyunsaturated fats contain?
More than one
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How can unsaturated oils and fats be hardened?
By reating with hydrogen in the presence of a nickel catalyst at 60'C (Hydrogenation)
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Which is healthier, saturated or unsaturated fats and why?
Unsaturated - they reduce amount of cholesteral in blood
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What are detergents the same as?
Emulsifiers
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What is used to remove stains when dry cleaning and how do they work?
Solvents - They bond with grease (due to both having weak intermolecular bonds) so when the solvent is removed, the grease moves with it
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When do biological detergents work best, and why?
At low temperatures - this is the optimum temp for the enzymes to work: they denature at higher temperatures
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Other cards in this set

Card 2

Front

What is used as an oxidising agent in the oxidisation of Iron (II) Salt?

Back

Chlorine gas

Card 3

Front

What do Iron atoms oxidise into when reacting with dilute acid?

Back

Preview of the front of card 3

Card 4

Front

What happens in a displacement reaction?

Back

Preview of the front of card 4

Card 5

Front

Is it the metal Ion or atom that is reduced during a displacement reaction?

Back

Preview of the front of card 5
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