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Chemistry IGCSE > Rates of Reaction > Flashcards

Rates of Reaction Flashcards

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1
Q

What factors can affect the rate of reaction

A
  • surface area
  • temperature
  • pressure
  • concentration
  • use of catalyst
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2
Q

Describe the effects of changes in the surface area of a solid to the rate of reaction

A
  • increasing surface area means there are more places for particles to collide
  • this leads to an increased frequency of collisions between the particles
  • resulting in a faster rate of reaction
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3
Q

Describe the effects of changes in the temperature of a solid to the rate of reaction

A
  • when particles are heated they have more kinetic energy and move around more
  • this leads to an increased frequency of collisions between the particles
  • resulting in a faster rate of reaction
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4
Q

Describe the effects of changes in the pressure in a gas to the rate of reaction

A
  • increasing pressure means there are more particles in a given volume
  • this leads to an increased frequency of collisions between the particles
  • resulting in a faster rate of reaction
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5
Q

Describe the effects of changes in concentration on the rate of reaction

A
  • increasing concentration means there are more particles in a given volume
  • this leads to an increased frequency of collisions between the particles
  • resulting in a faster rate of reaction
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6
Q

Describe the effects of using a catalyst on the rate of reaction

A
  • using a catalyst provides an alternate route for the reaction with a lower activation energy
  • this increases the proportion of particles with energy to react
  • resulting in a faster rate of reaction
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7
Q

What is a catalyst?

A

Catalysts are substances that speed up chemical reactions without being changed or used up during the reaction
- they do not appear in equations as they do not change the final product, only the rate at which the reaction happens

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8
Q

Test for oxygen

A
  • glowing splint relights
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9
Q

Test for hydrogen

A
  • squeaky pop over a lit splint
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10
Q

Test for carbon dioxide

A
  • bubble through limewater

- should turn cloudy

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11
Q

What are the ways to measure the rate of a reaction

A
  • mass loss at regular time intervals (using a balance scale)
  • volume produced at regular time intervals (using a gas syringe)
  • decreasing light (record time for cross to disappear)
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12
Q

What experiment can be used to prove temperature affects the rate of reaction?

A

Sodium thiosulfate experiment

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13
Q

In the sodium thiosulfate experiment, what is the:

  1. independent variable
  2. dependent variable
  3. control variables
  4. possible errors and solutions
A
  1. temperature
  2. time taken for cross to disappear
  3. concentration + volume of thiosulfate solution and acid
    • judgement of cross (use same person)
      - inaccuracy of temperature (water bath)
      - error in measuring acid (small increments at eye level)
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14
Q

What is the equation (word and symbol) for the sodium thiosulfate experiment

A
  • Sodium thiosulfate + hydrochloric acid = sodium chloride + sulphur dioxide + sulphur + water
  • Na2S2O3(aq) + 2HCl(aq) → 2NaCl(aq) + H2O(l) + SO2(g) + S(s)
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15
Q

What experiment can be used to prove concentration affects the rate of reaction?

A

Magnesium chloride experiment

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16
Q

In the magnesium chloride experiment, what is the:

  1. independent variable
  2. dependent variable
  3. control variables
A
  1. concentration
  2. rate of the volume of gas produced at regular time intervals
  3. -volume of acid (measure with a measuring cylinder)
    - mass of magnesium (weigh using a balance)
    - type/size of magnesium
    - temperature (same room and time)
17
Q

What is the equation (word and symbol) for the magnesium chloride experiment

A
  • magnesium + hydrochloric acid = magnesium chloride + hydrogen
  • Mg(s) + 2HCl(aq) → MgCl2(aq) + H2(g)
18
Q

What experiment can be used to prove surface area affects the rate of reaction?

A

Marble chips experiment

19
Q

In the marble chips experiment, what is the:

  1. independent variable
  2. dependent variable
  3. control variables
A
  1. surface area of the marble chips
  2. rate of mass loss over time (at regular intervals)
  3. -volume of acid (use measuring cylinder)
    - mass of chips (weigh using a balance)
    - concentration of acid (use same conc)
    - temperature (same room and time)
20
Q

Why is cotton wool used instead of a bung

A
  • cotton wool lets gasses escape but not any solution so prevents spillages
21
Q

What is the equation (word and symbol) for the marble chips experiment

A
  • Calcium carbonate + hydrochloric acid = calcium chloride + carbon dioxide + water
  • CaCO3 + 2HCl → CaCl2 + H2O + CO
22
Q

Describe a method for finding out the effect of surface area on rate of reaction

A
  1. weigh x amount of marble chips (calcium carbonate) into a conical flask and place onto a balance
  2. using a measuring cylinder, measure y amount of hydrochloric acid
  3. add all acid to the flask, placing cotton wool on the top and start the timer
  4. record mass of reaction every z seconds for at least v minutes
  5. repeat experiment using small marble chips
23
Q

Describe a method for finding out the effect of concentration on rate of reaction

A
  1. measure x grams of magnesium using a balance and add to a conical flask
  2. using a measuring cylinder, measure y amount of hydrochloric acid
  3. add all acid to the flask and start the timer
  4. read off and record the volume of the gas syringe every z seconds for at least v minutes
  5. repeat experiment using a higher concentration of acid
24
Q

Describe a method for finding out the effect of using a catalyst on rate of reaction

A
  • Set up the apparatus. Fill the measuring cylinder with water and hold it in position with a clamp.
  • Measure x cm3 of water using a measuring cylinder and pour into the conical flask.
    Measure y cm3 of 20-volume hydrogen peroxide solution using a small measuring cylinder. Add this to the conical flask.
  • Add a large spatula load of manganese dioxide powder to the flask.
  • Swirl and immediately fit the stopper and start the clock.
  • Note the time take to fill the measuring cylinder with gas. Record the results in the table below. Repeat the experiment with different catalysts.
25
Q

Catalyst experiment word and symbol equation

A 
Hydrogen peroxide = water + oxygen 
2 H2O2(l) = 2 H20() + O2(g)

Chemistry IGCSE (11 decks)

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