rates of reation

• What does the rate of chemical reactions refer to?

  The speed with which the reactants get turned into products
• What is an example of a slow chemical reaction?

  The rusting of iron
• What is a typical rate of reaction involving magnesium and an acid?

  A gentle stream of hydrogen bubbles
• How can we measure the rate of a chemical reaction?

  By measuring how fast reactants are used up or how fast products are formed
• What is the equation for the rate of reaction based on reactants used?

  Rate of reaction = quantity of reactants used / time taken
• What is the equation for the rate of reaction based on products formed?

  Rate of reaction = quantity of products formed / time taken
• What are the factors that affect the rate of chemical reactions?

  Temperature, concentration or pressure, surface area, and the presence or absence of a catalyst
• What is the theory behind chemical reactions known as?

  Collision theory
• According to collision theory, what must happen for particles to react?

  Particles must collide with each other with sufficient energy
• What is the term for the minimum energy required for a successful collision?

  Activation energy
• What happens if particles collide with less energy than the activation energy?

  They will bounce apart without reacting
• What two main factors determine the rate of a chemical reaction?

  The amount of energy the particles have and the frequency of collisions
• How does an increase in particle energy affect the rate of reaction?

  It increases the likelihood of surpassing the activation energy
• What effect does increasing the frequency of collisions have on the rate of reaction?

  It increases the number of successful collisions overall
• How does temperature affect the movement of particles in a reaction?

  Higher temperature increases particle movement and collision frequency
• What happens to the rate of reaction as temperature increases?

  The rate of reaction increases due to more successful collisions
• How are concentration and pressure related to the rate of reaction?

  Both increase the number of particles per unit volume, leading to more frequent collisions
• What is the effect of higher surface area on the rate of reaction?

  It increases the rate of reaction by providing more area for collisions
• If you wanted to increase the rate of reaction with magnesium and acid, which form of magnesium would you use?

  Powdered magnesium
• What is the role of a catalyst in a chemical reaction?

  It speeds up the reaction without being consumed in the process
• How does a catalyst affect the activation energy of a reaction?

  It lowers the activation energy by providing an alternative pathway
• What is shown in a reaction profile regarding catalysts?

  The change in chemical energy during a reaction
• What is the term for substances that can act as catalysts?

  Catalysts
• Which types of metals are commonly used as catalysts?

  Transition metals like cobalt and nickel
• What is the main focus of today's video?

  The video focuses on using graphs to measure the mean rate of a reaction and the rate of reaction at a specific time.
• What are enzymes in the context of catalysts?

  Enzymes are catalysts made by living organisms
• What are the four main factors that affect the rate of chemical reactions?

  • Temperature
  • Concentration or pressure
  • Surface area
  • Presence or absence of a catalyst
• How do temperature, concentration, pressure, and surface area affect the rate of reaction?

  • Increase energy of particles
  • Increase frequency of collisions
  • More successful collisions lead to a higher rate of reaction
• How can the rate of reaction be calculated?

  By dividing the amount of reactants used or the amount of product formed by the time taken for that change to occur.
• What is collision theory and its significance in chemical reactions?

  • States that particles must collide to react
  • Requires sufficient energy for successful collisions
  • Activation energy is the minimum energy needed for a reaction
• What is the role of a catalyst in a chemical reaction?

  • Speeds up the reaction
  • Not consumed in the reaction
  • Lowers activation energy by providing an alternative pathway
• If 1200 cm³ of hydrogen is produced in 4 minutes, what is the rate of reaction?

  The rate is 5 cm³ per second.
• What limitation does the average rate calculation have?

  It only gives the average rate during the time period, not the rate at specific moments.
• How does the rate of reaction change over time according to the video?

  The reaction starts fast and slows down as reactants are used up.
• What axes are used when plotting the volume of hydrogen produced against time?

  The x-axis represents time, and the y-axis represents the volume of hydrogen produced.
• What shape does the graph of hydrogen production initially take?

  The graph has a steep curve indicating a high rate of reaction.
• How do you calculate the mean rate of reaction over a specific period using a graph?

  By finding the amount of hydrogen produced during that period and dividing it by the time taken.
• What is the mean rate of reaction in the first three minutes if 1200 cm³ of hydrogen is produced?

  The mean rate is 6.67 cm³ per second.
• How do you find the rate of reaction at a specific time on the graph?

  By calculating the gradient of the tangent drawn at that point on the curve.
• What is a tangent in the context of a graph?

  A tangent is a straight line that touches the curve at a point and has the same gradient as the curve at that point.