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Chemistry > 9.6 Chemical Reaction Rates and Energetics > Flashcards

9.6 Chemical Reaction Rates and Energetics Flashcards

1
Q

What is a successful collision? [2]

A

Particles must collide with enough energy for a chemical reaction to happen.

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2
Q

What is activation energy? [2]

A

Minimum amount of energy needed for a reaction to happen

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3
Q

What is the symbol for activation energy? [1]

A

Ea

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4
Q

What is the rate of reaction? [2]

A
  • How fast the reaction goes
  • How often there are successful collisions
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5
Q

What two things does the rate of reaction depend on? [2]

A
  • the frequency of collisions
  • the energy of the collision
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6
Q

What things (factors) affect the rate of reaction? [5]

A
  1. concentration
  2. surface area
  3. temperature
  4. pressure
  5. catalysts
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7
Q

What is a catalyst? [2]

A

Increases the rate of reaction and is unchanged at the end of a reaction

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8
Q

What are practical ways to investigate the rate of reaction? [3]

A
  • change in mass of reactant
  • change in mass of product
  • formation of a gas
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9
Q

How is the rate of reaction increased if there’s a larger number of particles or if there’s an increase in pressure? [1]

A

more collisions

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10
Q

How is the rate of reaction increased if the surface area is increased? [1]

A

more space for a reaction

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11
Q

How is the rate of reaction increased if the temperature is increased? [1]

A

particles have more kinetic energy

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12
Q

How is the rate of reaction increased if there’s a catalyst? [1]

A

provides an alternate route to products from reactants (lower activation energy)

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13
Q

Do the reactants or the products have more energy? [1]

A

products

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14
Q

Where is the activation energy always between? [2]

A

reactants and the peak

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15
Q

Where is the overall energy change always between? [2]

A

reactants and products

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16
Q

What do reactants need to make products? [1]

A

additional energy from around them

17
Q

What is an exothermic reaction? [3]

A

It transfers thermal energy to the surroundings leading to an increase in the temperature of the surroundings

18
Q

What is an endothermic reaction? [3]

A

It takes in thermal energy from the surroundings leading to a decrease in the temperature of the surroundings

19
Q

What is the transfer of thermal energy during a reaction called? [1]

A

enthalpy change, ΔH, of the reaction

20
Q

What is ΔH like for exothermic reactions? [1]

A

negative

21
Q

What is ΔH like for endothermic reactions? [1]

A

positive

22
Q

What is ΔH? [1]

A

overall energy change of the reaction

23
Q

Which reactions are exothermic? [2]

A
  • neutralisation
  • displacement
24
Q

Which reactions can be endothermic? [2]

A
  • salt dissolving
  • precipitation
25
Q

Why is there a negative sign in exothermic reactions? [3]

A
  • exothermic reactions give out energy to their surroundings
  • temperature rise
  • negative sign shows that energy is given out
26
Q

Why is there a positive sign in endothermic reactions? [3]

A
  • endothermic reactions take in energy from their surroundings
  • temperature drop
  • positive sign shows that energy is taken in
27
Q

How do you know if a reaction if endo or exothermic in terms of bond breaking and bond making? [4]

A
  • if the energy taken in to break bonds is GREATER than the energy released in making bonds = ENDOTHERMIC
  • if the energy taken in to break bonds is LESS than the energy released in making bonds = EXOTHERMIC
28
Q

What should you measure to find the rate of reaction, in general? [2]

A
  1. amount of reactant used up per unit of time
  2. amount of product made per unit of time
29
Q

How does the speed of the rate of reaction affect the curve on a graph? [2]

A
  • the faster the rate of reaction = STEEPER curve
  • the slower the rate of reaction = SHALLOWER curve
30
Q

In exothermic reactions do the reactants have more or less energy than the products? [1]

A

more

31
Q

In endothermic reactions do the reactants have more or less energy than the products? [1]

A

less

32
Q

Between which two points does bond breaking occur? [1]

A

reactants and peak

33
Q

Between which two points does bond making occur? [1]

A

peak and products

34
Q

Between which two points is energy released or taken in? [1]

A

reactants and products

Chemistry (6 decks)

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