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53 Cards in this Set
- Front
- Back
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what is the unit of rate? |
Cm3/s |
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what two things do we need to measure to calculate rate? |
time and amount of reactant used/ amount of product formed |
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what do we call the minimum amount of energy needed for particles to react |
activation energy |
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What phrase do we use when answering questions about rate of reaction? |
amount of successful collisions |
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why does increasing the temperature increase the rate of reaction? |
Particles have more energy so they collide more often and with more energy. increases the amount of successful collisions |
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why does increasing the pressure (gases) or concentration (liquids) increase the rate of reaction |
particles collide more frequently so it increases the amount of successful collisions |
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how can you increase the surface area of a solid |
turn it into a powder |
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why does increasing tje surface area increase rate of reaction |
there are more surfaces for collisions to take place. so it increases the amount of successful collisions |
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what is a catalyst |
a substance which changws the rate of a reaction but it is not used up during the reaction |
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catalyst are specific. what does this mean? |
different reactions need different catalysts |
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why do industries like to use catalysts in their reactions |
reduces the costs |
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what do we mean exothermic reactions |
it transfers energy to the surroundings. They feel hot |
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what are some examples of exothermic reactions |
hand warmers, self heating coffee cans, combustion |
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what do we mean by endothermic reactions? |
it takes in energy from the surroundings, they feel cold |
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what are some examples of endothermic reactions? |
sports injury packs, thermal decomposition |
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what symbol is used to represent a reversible reaction? |
this |
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if the forward reaction is exothermic, what will the reverse reaction be? |
endothermic |
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what is the energy of the forwards reaction if thr reverse reaction is -80kJmol-1 |
+80kJmol-1, they always have the same amount of energy but opposite signs |
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what does te (s) symbol mean |
solid |
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what does the state (l) symbol mean |
liquid |
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what does the state symbol (g) mean |
gas |
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what does the state symbol (aq) mean |
aqueous (dissolved in water) |
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ph of an acid |
1-6 |
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ph of a base |
8-14 |
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alkalis are a special type of base. what makes them special? |
They are soluble (dissolved) in water |
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what are some examples of bases? |
metal oxides and metal hydroxides (s) |
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what are some examples of alkalis? |
metal hydroxides (aq) |
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how can you turn a soluble salt in a solution into a solid |
crystallise by evaporating off the water |
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why cant all metals react with acids to form salts |
some are too reactive and dangerous (like potassium) others are unreactive with acid (gold) |
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how can you tell when a salt is made when an acid and an alkali are reacted togehter |
use an indicator. a neutral solution will be made |
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acid +alkali |
salt +water |
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how can you made a salt from an acid and a base? |
keep adding the base to the acid until no more reacts, then filter off the leftover solid |
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what is a precipitate? |
an insoluble solid made by reacting two liquids together |
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how can precipitation be used? |
to remove unwanted ions from solutions. i.e drinking water or in treating effluent. |
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how do we name salts |
The first part of the name comes from the metal used, the second part from the acid |
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what salt name do you get for hydrochloric acid |
metal chloride |
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what salt name do you get for nitric acid? |
metal nitrate |
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what salt name do you get for sulphuric acid |
metal sulphate |
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ammonia dissolves in water to produce ammonium salts. what are they used for? |
fertilisers |
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what ions make a solution acidic? |
h+ |
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what ion makes a solution alkaline? |
OH- |
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what is the ionic equation for neutralisation? |
H+ + OH- H2O |
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what does electrolysis mean |
splitting a substance using electicity |
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what type of substances can be split up using electrolysis? |
ionic |
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why can solid substances not undergo electrolysis? |
the ions can't move, they have to be in solution or molten |
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where do positive ions go during electrolysis? |
the negative electrode as opposite charges attract |
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what does oil rig stand for |
oxidation is loss of electrons, reduction is the gain of electrons |
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what are the uses of electrolysis? |
elexctroplating, purifying copper, extraction of aluminium |
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what is the rule for the positive electrode? |
if chloride is present, chlorine is made, if not oxygen is made |
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what is the rule for the negative electrode |
the least reactive substance is made |
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why is cryolite used during electrolysis of aluminium oxide? |
to lower the melting point of aluminium oxide so less energy is needed to melt it |
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why does the positive electrode wear away during electrolysis of aluminium oxide |
oxygen is made at the positive electrode. The carbon electrode burns in the oxygen making carbon dioxide and so wearing away. |
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what are the three products of electrolysis of sodium chloride solution? |
chlorine gas, hydrogen gas, sodium hydroxide solution |
