rates of reaction and energy changes

• What is one way to follow a reaction?

  By looking at the loss of mass
• What happens to mass when a gas is produced in a reaction?

  The mass will decrease
• How can gas be collected during a reaction?

  Using a syringe or inverted measuring cylinder
• What are the units for measuring the rate of reaction when using volume and time?

  Centimeters cubed per minute
• What is the second unit for measuring the rate of reaction?

  Grams per second
• How do you find the rate of reaction at a specific point on a graph?

  By drawing a tangent at that point
• What does a steep tangent indicate about the rate of reaction?

  It indicates a fast rate of reaction
• What color change indicates a reaction between sodium thiosulfate and hydrochloric acid?

  From clear colorless to opaque
• What is a major health concern when conducting the sodium thiosulfate reaction?

  It can irritate your hands
• Why should the same person measure the rate of reaction in the color change experiment?

  To avoid differences in perception
• What is a potential error when collecting gas in a measuring cylinder?

  Gas already present in the cylinder
• How does the rate of reaction change with powdered calcium carbonate compared to large marble chips?

  It reacts much faster with powdered form
• How does temperature affect the rate of reaction?

  Higher temperature increases the rate
• What happens to particles at higher temperatures during a reaction?

  They move faster and collide more often
• How does surface area affect the rate of reaction?

  Larger surface area increases the rate
• What is the effect of high pressure or concentration on the rate of reaction?

  It increases the rate of reaction
• What is the role of a catalyst in a reaction?

  It lowers the activation energy
• What is the difference between endothermic and exothermic reactions?

  Endothermic absorbs energy; exothermic releases energy
• How does a catalyst affect the activation energy of a reaction?

  It lowers the activation energy required
• What is the energy change in an endothermic reaction?

  Energy is taken in
• What is the energy change in an exothermic reaction?

  Energy is given out
• How do you calculate the energy change during a reaction?

  By considering bond energies of reactants and products
• What is the balanced equation for burning hydrogen in oxygen?

  2H₂ + O₂ → 2H₂O
• What is the significance of a negative energy change in a reaction?

  It indicates an exothermic reaction
• What should you practice for the exam regarding calculations?

  Energy change calculations