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Flashcards in Rate equations Deck (23)
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1
Q

Rate equation

A

Rate = K [A]order [B]order

2
Q

Define order of a reaction

A

The power to which the conc of its reactant is raised in the reaction rate

3
Q

If [A] changes + rates stays the same

What is the order?

A

0

4
Q

If the rate is proportional to [A]

What is the order?

A

1

5
Q

If the rate is proportional to [A]2

What is the order?

A

2

6
Q

How do you work out the overall order of a reaction?

A

Add up the orders

7
Q

How do you find the orders of a reaction?

A

Experiments

8
Q

If the value of K inc, what effect does it have on the reaction?

A

Faster reaction

9
Q

What happens to K if you inc the conc of reactants?

A

Stays the same

10
Q

What happens to K if you inc the temperature?

A
  • K inc
  • Conc + orders stay the same
11
Q

What is the unit of K?

A

mol dm-3 s-1

12
Q

Define the initial rate of reaction and how to work it out

A
  • Rate at start of reaction
  • Conc-time graph, calculate gradient of tangent at time=0
13
Q

Suggest why initial rates are used to determine orders?

A

Conc are known

14
Q

How do you work out the rate equation?

A
  • Initials rate method:
  • Repeat experiment using diff. initial conc reactants
  • Calculate initial rate for each experiment
  • Work out how initial conc affects initial rate
15
Q

Define conitinious monitoring

A
  • Way to measure ROR
  • Following reaction til end by recording amount of product you have at regular interval
  • Used to work out how rate changes over time
16
Q

If a reaction mechanism has a series of steps, what is the overall rate dependent on?

A

Rate of the slowest step - Rate determining step

17
Q

What does it mean if a reactant appears in the rate equation?

A
  • Must affect rate
  • Involved w/ rate determining step
18
Q

Can catalysts appear in the rate equation?

A

Yes

19
Q

What does the order of a reaction show?

A

No. molecules involved in RDS

20
Q

What does the Arrhenius equation show?

A

How the rate constant varies w/ temp + Ea

21
Q

Arrhenius equation

A

k = Ae -Ea/RT

ln k = ln A - Ea/RT

  • k: rate constant
  • Ea: activation energy (j)
  • T: temp (K)
  • R: gas constant
  • A: arrhenius constant
22
Q

What is the formula to work out the activation energy using the arrhenius equation?

A

Ea = (ln A - ln k) x RT

23
Q

What happens to k when Ea inc?

A
  • Dec
  • Less particles have enough energy to react, less collisions = slower rate