Starter quiz
- How does increasing the concentration of reactants affect the rate of reaction?
- It decreases the frequency of collisions.
- It increases the frequency of collisions. ✓
- It has no effect on the rate of reaction.
- It decreases the energy of collisions.
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- Which of the following will not increase the rate of reaction?
- increasing the concentration of reactants
- increasing the surface area of solid reactants
- decreasing the temperature ✓
- increasing the pressure of reacting gases
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- In the collision theory, what does "successful collision" mean?
- any collision between reactant particles
- a collision that results in a reaction ✓
- a collision that increases the energy of particles
- a collision with no change in particles
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- What is the purpose of drawing a tangent to the curve on a rate of reaction graph?
- to find the total volume of gas produced
- to determine the average rate of reaction
- to find the instantaneous rate of reaction at a specific time ✓
- to measure the concentration of reactants
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- What does a flat horizontal line on a graph of volume against time indicate?
- The reaction is occurring rapidly.
- The reaction has stopped. ✓
- The reaction is occurring slowly.
- The reaction rate is increasing.
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- For most reactions, when is the rate of reaction highest?
- at the start ✓
- in the middle
- towards the end
- when the reaction has reached completion
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Exit quiz
- What does the gradient of the line on a graph of volume of gas produced against time represent?
- total volume of gas produced
- rate of reaction ✓
- time taken for reaction
- concentration of reactants
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- When plotting a graph of the volume of gas produced against time, how would the graph change if the concentration of the reacting solution is increased?
- The graph would be less steep.
- The graph would be steeper. ✓
- The graph would not change.
- The graph would be a constant horizontal line.
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- What happens to the rate of reaction when the concentration of reactants is doubled?
- It stays the same.
- It halves.
- It doubles. ✓
- It quadruples.
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- How can the gradient of the curved section on a rate of reaction graph be determined at a specific point?
- by calculating the area under the curve
- by drawing a horizontal line
- by drawing a tangent to the curve at that point ✓
- by measuring the distance between two points on the curve
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- If you use the same mass of magnesium and react it with different concentrations of excess acid, how will this affect the volume of gas produced?
- Different volumes of gas will be produced for different concentrations of acid.
- The same volume of gas will be produced for different concentrations of acid. ✓
- No gas will be produced for high concentrations of acid.
- Higher concentrations will produce higher volumes of gas.
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- If two experiments produce the same volume of gas but one reaction takes less time to complete, what can you say about the concentration of reactants?
- The reaction that took less time had a higher concentration of reactants. ✓
- Both reactions had the same concentration.
- The reaction that took more time had a higher concentration of reactants.
- Concentration does not affect reaction rate.
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Worksheet
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Presentation
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Video
Lesson Details
Key learning points
- The changing rate of a chemical reaction can be represented by a graph of volume of gas produced against time.
- When reacting excess acid, the same volume of gas is produced for equal amounts of magnesium.
- Doubling the concentration doubles the rate of reaction.
- The gradient of a rate of reaction graph can be calculated from a tangent drawn at a point on the curve.
Common misconception
Thinking that as the concentration of a solution in excess changes, so does the volume of gas produced.
The slide deck uses graphical data to show that the same volume of gas is produced when different concentrations are used, so long as the reacting solution is in excess.
Keywords
Gradient - The gradient on a graph represents the rate at which one quantity changes relative to another.
Rate of reaction - Rate of reaction is the speed with which a chemical reaction takes place.
Excess - A reactant in excess is present in a greater amount than is necessary to completely react with the limiting reactant.
Mean rate of reaction - The mean rate of reaction is the average rate at which reactants are converted into products in a given time.
Tangent - A tangent is a straight line that touches a curve at exactly one point without crossing it.
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