9943729
Description
Mind Map by Jumael Zafar, updated more than 1 year ago
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Created by Jumael Zafar
over 6 years ago
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Rate of reactions
- The general formula for the
rate of a reaction is: Amount
of product formed or amount
of reactants used divided by
time. This is basic.
- To be able to do this, you need
to continuously monitor a
reaction and record changes of
a certain variable over time.
- For example, you can measure the
mass of the reaction every 1
minute for a certain period, and
then repeat this at different
concentrations of a certain reactan.
- Reaction order tells you how changing the
concentration of a certain reactant changes
the rate.
- O order means it has no effect, first
order means the rate is directly
proportional to the concentration and
second order means the reaction is 2
squared (4) times faster.
- You work the rate out from time by doing 1
divided by time, if both rate doubles as
reactant concentration doubles, it is first
order etc.
- You work the rate out from time by doing 1
divided by time, if both rate doubles as
reactant concentration doubles, it is first
order etc.
- O order means it has no effect, first
order means the rate is directly
proportional to the concentration and
second order means the reaction is 2
squared (4) times faster.
- Reaction order tells you how changing the
concentration of a certain reactant changes
the rate.
- For example, you can measure the
mass of the reaction every 1
minute for a certain period, and
then repeat this at different
concentrations of a certain reactan.
- To be able to do this, you need
to continuously monitor a
reaction and record changes of
a certain variable over time.
- Rate using graph.
- YOU can also plot a graph of
concentration against time.
- To work out the rate, just work out the
gradient using, change in y divided by change in
x.
- To work out the rate, just work out the
gradient using, change in y divided by change in
x.
- YOU can also plot a graph of
concentration against time.
- The rate equation = k[A] to
the power of m x [B] to
the power of n.
- m and n are the
reaction orders e.g.
first or second. k is
the rate constant.
- m and n are the
reaction orders e.g.
first or second. k is
the rate constant.
- The initial rates method allows you to work out the rate
at 0 seconds by drawing a tangent if it's a curve and then
working out its gradient.
- The clock reaction
- This is where you measure the
time taken for a certain amount
of product to form while changing
the concentration of one
reactant.
- The iodine clock reaction uses Hydrogen
peroxide and Potassium Iodide to form
Iodine which instantly reacts with Sodium
Thiosulfate.
Annotations:
- Sulfuric acid is also required.
- Starch is added to mark the
endpoint when Sodium
Thiosulfate runs out. The
solution suddenly turns
blue-black as KI reacts with starch.
- Measure time taken for colour change
at different concentrations of Hydrogen
Peroxide and KI but make sure the
overall volume stays the same.
- Measure time taken for colour change
at different concentrations of Hydrogen
Peroxide and KI but make sure the
overall volume stays the same.
- The iodine clock reaction uses Hydrogen
peroxide and Potassium Iodide to form
Iodine which instantly reacts with Sodium
Thiosulfate.
- This is where you measure the
time taken for a certain amount
of product to form while changing
the concentration of one
reactant.
- The rate-determining step
- Some reactions often
have two or more steps.
- You have to find the slower of the two steps.
- This will be the rate-determining step.
- This will be the rate-determining step.
- You have to find the slower of the two steps.
- Some reactions often
have two or more steps.
- The Arrhenius equation
- The rate constant = Ae to the
power of -Ea/RT
Annotations:
- A = The Arrhenius constant e = The exponential of... Ea = Activation energy R = the gas constant (8.31) T = Temperature (K)
- The rate constant = Ae to the
power of -Ea/RT
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