Reaction rates

• What is the aim of the experiment measuring gas production?

  Investigate effects on reaction rates
• What reaction is being studied in the gas production experiment?

  Hydrochloric acid and marble chips
• What equipment is needed for measuring gas production?

  • Gas syringe and clamp stand
  • Measuring cylinder and water trough
  • Delivery tube and bung
  • Conical flask
  • Measuring cylinders (100 cm​3​ and 25 cm​3​)
  • Timer
  • Digital balance and weighing boat
  • Pestle and mortar
• What chemicals are required for the gas production experiment?

  Hydrochloric acid and marble chips
• What is the first step in the gas production experiment method?

  Set up the apparatus as shown in figures
• How much dilute hydrochloric acid should be added to the conical flask?

  50 cm​3​
• What should be done immediately after adding marble chips to the conical flask?

  Attach the bung and start the timer
• How should the results be recorded during the gas production experiment?

  Record time for every 10 cm​3​ of gas
• What must be controlled for a fair test in the gas production experiment?

  Concentration, volume of HCl, mass of chips
• What gas is collected during the gas production experiment?

  Carbon dioxide
• What is the chemical equation for the reaction in the gas production experiment?

  2HCl(aq) + CaCO​3​(s) ⟶ H​2​O(l) + CaCl​2​(aq) + CO​2​(g)
• Why must the bung be attached immediately?

  To minimize gas escape
• What should be done before adding marble chips to the measuring cylinder?

  Ensure it is filled with water
• How does the gas volume measurement work with an upturned measuring cylinder?

  Gas displaces water in the cylinder
• How does increasing hydrochloric acid concentration affect reaction rate?

  Increases rate due to more frequent collisions
• How does increasing the surface area of marble chips affect reaction rate?

  Increases rate due to more exposed particles
• What safety precautions should be taken when crushing marble chips?

  Wear safety goggles and crush gently
• What should be done with chemical spillages?

  Clean up immediately
• Why is hydrochloric acid considered corrosive?

  It can damage skin and materials
• What is the formula for calculating the rate of reaction in the gas production experiment?

  Rate of reaction = Volume of gas / Time
• What should the graph of volume of gas produced against time look like?

  It should produce a curve
• What does the gradient of the tangent to the curve represent?

  The rate of reaction at that time
• What is the aim of the experiment observing color change?

  Investigate effects on reaction rates
• What equipment is needed for observing color change?

  • Measuring cylinders (50 cm​3​ and 10 cm​3​)
  • Conical flask (250 cm​3​)
  • Piece of paper
  • Black marker pen
  • Timer
  • Thermometer
  • Water bath
  • Test tube
• What chemicals are required for the color change experiment?

  Sodium thiosulfate and hydrochloric acid
• What is the first step in the color change experiment method?

  Measure sodium thiosulfate and pour into flask
• What should be done with the conical flask during the color change experiment?

  Place it over a marked cross
• What should be done immediately after adding hydrochloric acid to the flask?

  Swirl the flask and start the timer
• Why is it important to record the initial temperature of the mixture?

  To analyze the effect of temperature on reaction
• What indicates the end of the reaction in the color change experiment?

  When the black cross is no longer visible
• How can different starting temperatures be achieved in the color change experiment?

  Using a water bath for reactants
• What is the chemical equation for the color change reaction?

  Na​2​S​2​O​3​(s) + 2HCl(aq) → 2NaCl(aq) + H​2​O(l) + SO​2​(g) + S(s)
• What is the yellow-white precipitate formed in the color change reaction?

  Sulfur, S(s)
• How does increasing initial temperature affect the reaction rate?

  Increases rate due to more kinetic energy
• Why is the method for determining the rate of reaction considered low accuracy?

  It is subjective based on observation
• What should be done to increase accuracy in the color change experiment?

  Same person should observe the reaction
• What safety precaution should be taken regarding sulfur dioxide?

  Avoid inhaling and ensure ventilation
• What should be done with breakages or spillages in the lab?

  Clean up immediately
• What is the formula for calculating the rate of reaction in the color change experiment?

  Rate of reaction (s​-1​) = 1000 / Time
• How can results from the color change experiment be recorded?

  In a table with temperature and reaction time