Karteikarten
AQA GCSE Additional Science Chemistry
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- 1How do you find out the charge of an ion?LOOK AT ITS GROUP NUMBER
Group 1 = 1+ (needs to lose 1)
Group 2 = 2+ (needs to lose 2)
etc. so all +vely charged up to group 5.
Group 6 = -2
Group 7 = -1 - 2What is an ion?An atom that has lost/gained electrons.
- 3What is a reversible reaction?A reaction in which the products can re-form the reactants.
Can never get a 100% percentage yield. - 4What is the rate of a reaction?The change in concentration of a reactant or product in a given time.
- 5How does increasing the temperature affect the rate of reaction?Particles will have more energy and move quicker. (in metals - ions vibrate more) so will collide with more energy. Higher frequency of successful collisions so reaction will be faster.
- 6How does increasing the concentration affect the rate of a reaction?More particles per unit of volume, higher frequency of collisions, faster reaction.
- 7How does increasing the pressure increase the rate of a reaction?More particles within a given volume, higher frequency of collisions, faster reaction.
- 8How does increasing the SA increase the rate of a reaction?More space to react, higher frequency of successful collisions, so reaction is faster.
- 9Acid + metal --> ??+???Salt and Hydrogen
- 10Acid + Alkali --> ??+?? Acid + Base --> ??+??Salt + water.
- 11How to make insoluble salts.Add lead nitrate to potassium iodide.
Ions in the 2 solutions react. (Pb^2+ and I^-)
Lead iodide is created.
Lead iodide is insoluble (it's a solid precipitate) so it precipitates out of solution.
Filter precipitate.
Wash (e.g. w/distilled water) and dry precipitate. - 12How to extract aluminiumAluminium oxide is electrolysed.
Cryolite is mixed with aluminium oxide to lower its melting point by around 1/2.
Al forms at -ve electrode.
Ocygen formed at +ve electrode.
+ve carbon electrodes replaced regularly as they react with oxygen to form CO2 and gradually burn away. - 13Why would the calculated yield of a reaction not be obtained?Not fully reacted.
Gases lost to air.
Impurities in the reactants. - 14How to make Soluble Salts Using Acid + Insoluble Base -> (soluble) Salt + WaterAdd copper oxide (IB) to sulphuric AcCID.
Warm and stir mixture until reaction is over i.e. some copper oxide's left.
Filter solution through filter paper.
Add copper sulphate solution to evaporating dish over beaker of water.
Heat beaker.
leave to sit for a few days.
Copper sulphate will evaporate. - 15What is collision theory?The reacting particles need enough energy (the activation energy) to react when they collide.
- 16What is the activation energy?The smallest amount of energy that particles must have before they can react.
- 173 Advantages of Using Catalysts1. Cheaper to use a catalyst than to pay for extra energy required for higher temperatures/pressures.
2. They can be used over and over again without being used up or chemically changed.
3. Can lower production costs for making particular products. - 182 Disadvantages of Using Catalysts1. They're often very expensive metals e.g. gold or platinum
2. They're often transition metals or their compounds, which are often toxic and can harm the environment if they escape. - 19How would you measure the rate of a reaction?The amount of reactant used/time
The amount of product formed/time - 204 Developments of Using Catalysts in Industry1. Chemists are working to develop new catalysts that are harmless to the environment.
2. They can now follow the reactions that happen on the surface of metals in a catalytic converters. Knowing how they take place will help them design new catalysts.
3. Chemists can now make catalysts used in making drugs without the precious metal.
4. Enzymes can be used as catalysts. - 21What are exothermic reactions?Energy is transferred FROM the reacting chemicals TO their surroundings.
Energy transferred heats up the surroundings; there is a rise in temperature. - 22What are endothermic reactions?Energy is transferred FROM the surroundings TO the reacting chemicals.
There is a drop in temperature. - 233 Examples of Exothermic Reactions1. Respiration
2. Neutralisation
3. Combustion - 24Example of an Endothermic ReactionThermal decomposition
- 25How can we use the energy from exothermic reactions in a disposable hand warmer?Oxidation of iron releases energy. Iron turns into hydrated iron oxide in an exothermic reaction. NaCl is used as a catalyst.
Can only be used once but lasts for a few hours. - 26How can we use the energy from exothermic reactions in a reusable hand warmer?Based on formation of crystals from solutions of a salt (often sodium ethanoate).
A supersaturated solution is prepared. We do this by dissolving as much of the salt as possible in hot water and allowing the solution to cool.
Small metal disc in plastic pack starts exothermic change. When pressed, small particles of metal are scraped off, starting crystallisation which give out energy. - 27How would you re-use a reusable hand warmer?Put solid back into boiling water to re-dissolve the crystals and wait for it to cool down.
- 28How can we use the energy from exothermic reactions in self-heating cans? Give some disadvantages.Press button in base of can. This breaks seal, allows water and calcium oxide to mix.
Development took years and cost millions of pounds. In early versions, temperature of coffee didn't rise high enough. - 29How can we use cooling effect of endothermic reactions in cold packs for sports injuries? (can also be used to chill drinks cans)Chemical cold packs contain ammonium nitrate and water.
Ammonium nitrate dissolves and takes in energy.
Advantages:: Are ideal where there is no ice available to treat knock/strain.
Disadvantages: Can only be used once - 30What's the name of the substance broken down in electrolysis?The electrolyte
- 31What is formed in the electrolysis of brine (sodium chloride and water)? Where are these substances formed?Hydrogen - at the -ve electrode as formed from H+ ions.
Chlorine - at the +ve electrode as formed from Cl- ions.
Sodium Hydroxide solution - 32Test for Hydrogen 3 Uses of HydrogenProduces squeaky pop with lit splint
As a fuel, to make ammonia, harden margarine - 33Test for Chlorine Uses of ChlorineBleaches damp litmus paper.
Sterilises swimming pools - 34Test for Sodium Hydroxide Uses of Sodium HydroxideLitmus paper turning paper, showing it's alkaline
Oven cleaner and making bleach - 35What are acids?Substances that produce H+ ions when we add them to water.
- 36What are bases?Substances that will neutralise acids.
They include alkalis, metal oxides and metal hydroxides. - 37What are alkalis?A soluble hydroxide.
A base that can dissolve in water.
Produce OH- ions when we add them to water. - 38Why do we electroplate objects? 3 reasonsTo improve their appearance
To protect their surface
To use smaller amounts of precious metals. - 39Explaining Electroplating (What should be used as each electrode, what happens at each electrode)The object to be plated should be the -ve electrode.
The object you'll plate it with should be the +ve electrode.
At +ve electrode: Atoms are oxidised. Form nickel ions which go into the solution.
At -ve electrode: Ions from solution are reduced. Form atoms which are deposited on the electrode. - 40How to Make Soluble Salts (using Acid + Alkali -> Salt + Water)Measure out how much alkali you want.
Flask contains alkali and indicator.
Add acid until indicator goes green, while measuring how much acid you've added.
Repeat experiment without indicator, adding the right amount of acid and alkali. We know solution is now neutral.
Put solution into evaporating dish and heat above beaker of water.
Leave solution for few days on side to form into salt crystals. - 41Uses of Precipitation ReactionsTreating Effluent (waste produced by factories): Reacts ions to produce a solid substance that can then be filtered
- 42What is the +ve electrode called?The anode
- 43What is the -ve electrode called?The cathode
- 44What happens at the +ve electrode?Oxidisation
-ve ions lose electrons. - 45What happens at the -ve electrode?Reduction
+ve ions gain electrons.
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- AS Level Science Karteikarten am AQA GCSE Additional Science Chemistry , erstellt von Charlie Murray am 10/05/2015.
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