Chemistry C6 (The rate and extent of chemical change)

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what is measured to measure the rate of a chemical reaction?
quantity of ractant used or quantity og product formed over time
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what are the 2 equations to calculate rate of reaction?
quantity of reactant used/time taken and quantity of product formed/time taken
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how may the quantity of reactant/product be measured by?
mass in grams, by a volume in cm^3, in terms of moles
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what are the unit/s of rate of reaction?
g/s, cm^3/s, mol/s
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what are the factors that affect the rate of reaction?
concentrations of reactants, pressure of reacting gases, surface area of solid reactants, temperature and the presence of catalysts
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what happens when the concentration of reactants or pressure of reacting gas increases?
reactant particles become more crowded, the frequency of collisions between reactant particles increases, so rate of reaction increases
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if the concentration or pressure is higher, what will the gradient look like?
it will be steeper
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what happens to a lump if it is divided into a powder?
volume stays the same, area of exposed surface increases, surface area to volume ration increases
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what happens if the surface area (to volume ratio) of a reacting solid increases?
more reactant particles are exposed at the surface, the frequency of collisions between reactant particles increases, so rate of reaction increases
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if the surface area is greater, what will the gradient and time taken to finish reaction look like?
it will be steeper and it will finish sooner
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what happens if the temperature of the reaction mixture is increased?
reactant particles move more quickly, energy of particles increases,frequency of successful collisions between reactant particles increases, proportion of collisions which are successful increases, so the rate of reaction increases
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whta does a successful collision mean?
a collision between reactant particles with enough energy to produce a reaction
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on a graph, what would the reaction with the higher temperature give?
a steeper gradient and would finish sooner
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what is activation energy?
the minimum amount of energy that particles must have to react
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what do catalysts do to the rate of reaction?
they change the rate of reaction and are not used up
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how do catalysts increase the rate of reaction?
by providing a different pathway for the reaction that has a lower activation energy
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how would the size of a curve in a reaction profile with a catalyst differ from one without a catalyst?
would be a smaller curve
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are catalysts included in the chemical equation for the reaction?
no
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how can the direction of a reversible reaction be changed?
by changing the conditons
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if one direction in a reversible reaction is endothermic, what must the other direction be?
exothermic
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how does the amount of energy transferred change when the direction changes?
the same amount of energy is transferred in each case
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how can equilibrium be reached?
by getting the froward and reverse reactions to occur at exactly the same rate
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what happens if the concentration of a reactant is increased?
more products will be formed until equilibrium is reached again
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what happens if the concentration of a reactant is decreased?
more reactants will react until equilibrium is reached again
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what happens if the temperature of a system at equilibrium is increased?
amount of products increases for endothermic, amount of products decreases for exothermic
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what happens if the temperature of a system at equilibrium is decreased?
amount of products decreases for endothermic, amount of products increases for exothemric
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what does an increase in pressure cause the equilibrium position to shift towards?
the side with the smaller number of molecules
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what does an decrease in pressure cause the equilibrium position to shift towards?
the side with the larger number of molecules
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Other cards in this set

Card 2

Front

what are the 2 equations to calculate rate of reaction?

Back

quantity of reactant used/time taken and quantity of product formed/time taken

Card 3

Front

how may the quantity of reactant/product be measured by?

Back

Preview of the front of card 3

Card 4

Front

what are the unit/s of rate of reaction?

Back

Preview of the front of card 4

Card 5

Front

what are the factors that affect the rate of reaction?

Back

Preview of the front of card 5
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