Rates of reaction

• What should you be able to do by the end of the video?

  Draw and interpret graphs of reactants/products
• What does the slope of the graph represent in a chemical reaction?

  The rate of reaction
• What happens to the slope of the graph as the reaction proceeds?

  The slope becomes less steep
• Why does the reaction slow down over time?

  Fewer reactant molecules are available
• What does a flat line on the graph indicate?

  The reaction has stopped
• How is the quantity of product measured if it is a gas?

  In centimeters cubed
• What are the two ways to measure the rate of a chemical reaction?

  • Quantity of product formed
  • Quantity of reactant used
• How do you calculate the mean rate of a reaction?

  Quantity of product divided by time
• What is the mean rate of reaction if 60 grams of product is formed in 15 seconds?

  4 grams per second
• What is the mean rate of reaction if 20 grams of product is formed in 40 seconds?

  0.5 grams per second
• What is the quantity of product formed in a chemical reaction measured in?

  Grams or centimeters cubed
• Why does the slope of the graph showing the quantity of product formed over time decrease over time?

  Because the reaction is slowing down as fewer reactant molecules are available
• What does a flat slope on the graph of quantity of product formed over time indicate?

  The reaction has stopped as all reactants have been used up
• How do you calculate the mean rate of a chemical reaction?

  Mean rate = Quantity of product formed / Time taken
• In a chemical reaction, 20 grams of product was formed in 40 seconds. What is the mean rate of reaction?

  0.5 grams per second
• In a chemical reaction, 150 grams of reactant was used in 75 seconds. What is the mean rate of reaction?

  2 grams per second
• What is the formula to calculate the mean rate of a chemical reaction?

  Mean rate = Quantity of product formed / Time taken
• How does the graph of quantity of product formed over time change during a chemical reaction?

  • Initially, the slope is steep indicating a fast reaction rate
  • Over time, the slope becomes less steep as the reaction slows down
  • Eventually, the slope becomes flat indicating the reaction has stopped as all reactants are used up
• How do you calculate the mean rate of a chemical reaction from the quantity of reactant used?

  • Mean rate = Quantity of reactant used / Time taken
• How does the information provided in a graph of quantity of product formed over time differ from a graph of quantity of reactant used over time?

  The graphs show the same information, just from the perspective of the product formed vs the reactant used
• What are the key differences between using the quantity of product formed vs the quantity of reactant used to calculate the mean rate of a chemical reaction?

  • Calculating from product formed: Mean rate = Quantity of product formed / Time taken
  • Calculating from reactant used: Mean rate = Quantity of reactant used / Time taken
  • Both methods give the same mean rate, just from different perspectives
• What is the first derivative of $x^2$?


  $2x$
• What are the strengths and weaknesses of qualitative research methods?

  Strengths:

  • Provides in-depth, rich data
  • Flexible and adaptable to new information
  • Captures complex phenomena

  
  

  Weaknesses:

  • Time-consuming and labor-intensive
  • Potential for researcher bias
  • Limited generalizability
  • Difficulty in replicating results
• How does photosynthesis work in plants?

  Process of photosynthesis:

  1. Light absorption by chlorophyll
  2. Light-dependent reactions: water splits, electrons excited
  3. Electron transport chain: ATP and NADPH produced
  4. Calvin cycle (light-independent reactions):

  • CO2 fixation
  • Reduction of fixed carbon
  • Regeneration of RuBP

  1. Glucose and other carbohydrates synthesized
• What are the steps of the scientific method?

  1. Ask a question
  2. Do background research
  3. Construct a hypothesis
  4. Test the hypothesis by doing an experiment
  5. Analyze the data and draw a conclusion
  6. Communicate the results
• What are the main components of the cell membrane?

  • Phospholipid bilayer
  • Proteins (integral and peripheral)
  • Cholesterol
  • Carbohydrates (in glycoproteins and glycolipids)
• What should you be able to do by the end of the video?

  Draw tangents on the rate of reaction graph
• How can the slope of the tangent be used in this context?

  As a measure of the rate of reaction
• What should higher-tier students be able to calculate regarding the tangent?

  The gradient of a tangent at a specific point
• What happens to the rate of reaction initially?

  The reaction is extremely fast
• What does the slope of the graph indicate?

  The rate of the reaction
• What does the changing slope of the curve indicate?

  The rate is constantly changing
• How do scientists measure the rate of reaction at a specific point?

  By drawing a tangent that touches the curve
• What is the straight line that touches the curve called?

  A tangent
• What does the slope of the tangent represent?

  The rate of reaction at that point
• What does a steeper slope of the tangent indicate?

  The reaction is faster at that point
• What is the vertical side of the triangle used for in the tangent calculation?

  It measures the change in product mass
• How do you find the length of the vertical side of the triangle?

  By reading from the y-axis
• What does the horizontal side of the triangle measure?

  The change in time
• How do you find the length of the horizontal side of the triangle?

  By reading from the x-axis