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Rate of reaction - Coggle Diagram
Rate of reaction
Catalysts
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they increased the are buy providing a different pathway for the reaction that has a lower activation energy
when present - particles require less energy to over come the activation energy with means more particles can successfully collide per second
we don't include these in the chemical equation for a reaction as they aren't used up and aren't reactants
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Mean rate of reaction
on a graph showing quantity of product formed over time, the slope of the line gives is an idea of the rate of the reaction - steeper = faster reaction
initially rate is fast because we have a large number if reactant molecule - lots reacting and forming product
gradually the slope becomes less steep and the rate of reaction is decreasing because lots of the reactant molecules have already reacted and turned into product
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the slope of the line at the end is flat due to all of the molecules being reacted and the rate of reaction being 0
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effect of temperature
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if particles with low energy collide, they cannot overcome the activation energy barrier and wouldn't collide successfully and a reaction would not occur
if 2 particles with a larger amount of energy collide, they have enough energy to over come the activation energy barrier and will collide successfully and this results in a reaction
increasing the temp increases the rate of reaction as temp will increase the energy of the particles and they will move faster which increases the frequency of collision (greater num of collisions per second)
each collision has more energy and more particles can over come activation energy and collide successfully
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reversible reactions
if an arrow in a chemical equation point in one direction that means that it is not reversible and cant be turned back into the reactants
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we can change direction of reversible reactions by changing the conditions e.g forward by heating it and backwards by cooling it down
if a reaction is exothermic in one directions its endothermic in the opposite direction and the same amount of energy is transferred
hydrated copper sulfate (blue) is heated to form anhydrous copper sulphate (white) and this also produced water. energy is put in which tells us that the forward reaction is endothermic. is we add the water back into the anhydrous copper sulphate back in then the reaction reverses and energy is released and is exothermic
equilibrium - when the rate of the forward id equal to the rate of the reverse reaction in a closed system where no substances or energy can enter other escape e.g in a sealed container
RATES REQUIRED PRACTICAL
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6) stop the clock once the cross cant be seen and carry out the experiment again using lower concentrations on sodium thiosulfate
7) repeat the whole experiment and calculate the mean values for each concentration of sodium thiosulfate solution
reproducibility is when a method can be repeated by another person or using a different technique or equipment and still get the same result - different people have different eye sight and some may see the cross for longer and get a different result - all student use a printed cross and this problem may not be too great
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7) every 10s, measure volume of hydrogen gas in the measuring cylinder and continue until no more is given off
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finding is reproducible ad the they both show the higher the concentration the faster the reaction takes place
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Using tangents
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at a point of measurement that we want to use to find the rate, you would draw a straight line line called a tangent to find it
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