Triple Science - Chemistry - Paper 2

• How is the rate of a chemical reaction defined?

  Speed of the reaction
• How can the rate of a reaction be measured?

  By reactants used or products made
• What is the formula to calculate the rate of a reaction?

  Amount divided by time
• If a reaction produces 20 cm³ of gas in 2 seconds, what is the rate?

  10 cm³ per second
• What does the term "per" in units indicate in calculations?

  Division of one quantity by another
• How can you determine the rate from a rate graph?

  By calculating the gradient of the graph
• What does a steeper gradient on a rate graph indicate?

  A faster rate of reaction
• How does a curved graph differ from a straight line in terms of reaction rate?

  The rate changes over time on a curved graph
• How can you calculate the mean rate from a graph?

  By using start and end values
• What is a tangent in the context of a graph?

  A line that touches the graph at one point
• How do you calculate the rate using a tangent?

  Change in y divided by change in x
• What is collision theory?

  Reactions occur when particles collide
• What is activation energy?

  Minimum energy needed for a reaction
• How can you speed up a reaction rate?

  By increasing pressure, concentration, or temperature
• How does increasing pressure affect reaction rates?

  Particles collide more frequently
• How does concentration affect reaction rates?

  Higher concentration leads to more collisions
• What happens to surface area when a solid is cut into smaller pieces?

  Overall surface area increases
• How does temperature influence particle movement?

  Higher temperature increases particle speed
• What is the role of a catalyst in a reaction?

  Speeds up the reaction without being used
• What is an example of a biological catalyst?

  Enzymes
• How do catalysts affect activation energy?

  They provide a lower activation energy pathway
• What is an exothermic reaction?

  Releases energy to the surroundings
• What is an endothermic reaction?

  Absorbs energy from the surroundings
• What happens to a reversible reaction at equilibrium?

  Forward and backward reactions occur at the same rate
• What does Le Chatelier's principle state?

  Systems respond to counteract changes
• How does adding a reactant affect equilibrium?

  Shifts equilibrium to remove the reactant
• How does pressure affect equilibrium in a reaction?

  Shifts towards the side with fewer gas molecules
• What happens when you heat a reaction at equilibrium?

  System favors the endothermic reaction
• What is the effect of decreasing pressure on equilibrium?

  Shifts towards the side with more gas molecules
• What is the significance of a solid precipitate in a reaction?

  Indicates a reaction has occurred
• How can you monitor the rate of a reaction that becomes turbid?

  By timing how long a cross disappears
• What is the importance of controlling variables in an experiment?

  Ensures the experiment is valid
• What is the typical reaction used to measure turbidity?

  Hydrochloric acid and sodium thiosulfate
• What does a double-headed arrow indicate in a chemical equation?

  Reversible reaction
• How does heating hydrated copper sulfate affect its state?

  Turns it into anhydrous copper sulfate
• What happens when water is added to anhydrous copper sulfate?

  It becomes hydrated copper sulfate
• What is equilibrium in a closed system?

  Forward and backward reactions occur at the same rate
• What does it mean if the concentrations of reactants and products stop changing?

  Equilibrium has been reached
• How can you identify equilibrium on a graph?

  Point where the graph flattens out
• What is the effect of adding more hydrochloric acid in a reversible reaction?

  Shifts equilibrium to favor products