spd of reaction Flashcards

1
Q

fast vs slow reaction egs

A

fast reaction
neutralisation
slow reaction
rusting

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2
Q

define marble chips

A

calcium carbonate
limestone
CaCo3

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3
Q

methods for measure rate of reaction

A
  1. loss in mass, balance
  2. use a gas syringe
  3. water displacement (count volume not bubbles)
  4. KI turn, colourless -> brown
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4
Q

when using loss of mass method must…

A

tare electronic balance

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5
Q

why loss in mass method always decrease in mass

A

() gas escaped

cotton wool in setup is porous

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6
Q

purpose of cotton wool in loss of mass method

A
  • cotton wool porous, allow () gas escape, result loss of mass
  • efferverscence, acid + () reaction, acid may leave conical flask, acid spray
  • prevent mass decrease due to acid spray
  • inaccurate result
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7
Q

loss of mass method
what data to collect

A

mass of mixture in fixed time interval

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8
Q

measure rate of reaction
reaction nvr produce gas, only produce precipitate

A

use aq. potassium iodide

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9
Q

which reaction
as time passes by, rate of reaction decreases

A

neutralisation

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10
Q

5 things that can change rate of reaction

A
  1. particle size
  2. concentration/number of particles per unit volume
  3. pressure
  4. temperature
  5. catalyst

When limting reactant added, increase yield.

1, 2, 3 -> increase freq of collision
5 -> increase freq of effective collision

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11
Q

does increase of mass and volume change rate of reaction?

A

no

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12
Q

collision theory

A
  1. for reaction to take place
  2. particles must collide with sufficient energy
  3. reach activation energy

https://docs.google.com/document/d/1Ep_FO9CxYSFbxmf3Zqg9mgm9NNyt2enpfMDr49gufrU/edit?tab=t.0 page 22

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13
Q

what is effective collision
collision theory

A

new products are formed

i.e.
AA + BB -> AB + AB effective

AA + BB -> AA + BB ineffective, no reaction occured, no new product formed

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14
Q

how particle size affect rate of reaction

A
  1. particle size, solid reactant decreases, increases SA:Vol ratio, reactants

STANDARDISED
2. increase rate of collision
3. increase freq of effective collision, reactant particles
4. rate of reaction increase

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15
Q

how higher conc. of particles affect rate of reaction

A
  1. more particles per unit volume
  2. distance btwn particles shorter
  3. collisions, proportional 2 no. particles present

  1. increase rate of collision
  2. increase freq of effective collision
  3. rate of reaction increase

When limiting reactant added, yield increases

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16
Q

how higher pressure affect speed of reaction?

A
  1. pressure only affect reactions involving gases
  2. higher pressure, greater number of reacting particles per unit volume

  1. increase rate of collision
  2. increase probability, rate of effective collision, reactant partcles
  3. increase rate of reaction
17
Q

how catalyst affect speed of reaction

A

provide alternative pathway for reaction w/ lower activation energy

18
Q

how temperature affect speed of reaction

A
  1. temp, reaction increase
  2. reacting particles gain kinetic energy, move faster
  3. particles collide w/ each other more, freq of collisions increase
  4. proportion of particles, kinetic energy overcome Activation Energy increase,
  5. freq effective collision increase
  6. rate of reaction increase
  7. small increase temp can mean large increase, rate

this is best factor to increase spd of reaction
- increase freq of collision
- increase rate of effective collision
- can be used, all 3 states

19
Q

decrease particle size -> increase spd of reaction

which state can use?

20
Q

increase conc -> increase spd of reaction

which state can use?

21
Q

increase pressure -> increase spd of reaction

which state can use?

22
Q

catalysts
characteristics

A
  • can change in states aft reaction (phys)
  • increase rate of reaction, not yield
  • specific in action, diff catalyst for diff reactions
  • req in small amt → not used up, reaction
  • effectiveness hindered by impurities

rest from bio
- remain chemically unchanged aft chemical reaction
- specific in (their reactions)

23
Q

volume of product produced // time graph

gradient of graph represent…

A

rate of reaction

24
Q

e.g. catalysts

A

Fe -> making ammonia
Pt (Platinum) -> making HNo3
Pd (Palladanium)

25
Q

e.g. biological catalysts

A

bacteria spd up manufacture cheese bread

26
Q

why rate of reaction slow down as time passes?

A
  • reactants are being used up,
  • conc. of reactants are decreasing with time
27
Q

what is yield in a reactant released plotted against time graph?

A

reactant released

28
Q

why collision unsuccessful

A

particles did not collide with sufficient energy, reach Ea

29
Q

why increase rate of reaction

A
  1. economic interest
  2. higher rate, production
  3. more efficient, sustainable
30
Q

aq/gaseous reactants approx. ___deg celc increase, rate of reaction x2

31
Q

desc graph
increase all 5 factors

  1. particle size
  2. concentration/number of particles per unit volume
  3. pressure
  4. temperature
  5. catalyst
A
  1. compared to reaction w/ (decreased sa:vol/pressure/temp),
  2. graph for same reaction w/ (increased sa:vol /pressure/temp),
  3. steeper gradient, start, horizontal sooner

steeper gradient: increased rate of reaction. Yield does NOT increase.
horizontal sooner: (limiting) reactant particles completely used up in reaction quicker

32
Q

ALWAYS WRITE FOR ENZYMES

A

remain chemically unchanged after reaciton

33
Q

when measuring gas periodically, must add

A

measure volume of gas (left/released)

34
Q

how to make experiment, decide effect of (factor) on rate of reaction

A
  1. record time taken for (5(u) gas collected/lost/indicator color change),
  2. increasing (factor) when repeating exp.
35
Q

increase conc. always increase rate?

A

no. e.g.
zero order rate reactions