Rates of reaction and energy changes

    Cards (41)

    • What topic is emphasized for exam preparation?
      Rates of reactions
    • Why is it important to pay attention to rates of reactions?
      They are frequently asked in exams
    • What are the different ways to follow a reaction?
      • Loss of mass
      • Volume of gas produced
      • Color change
    • How can you measure the loss of mass in a reaction?
      By adding solid to a liquid
    • 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 units are used for measuring the rate of reaction involving volume and time?
      Centimeters cubed per minute
    • What units are used for measuring the rate of reaction involving mass and time?
      Grams per second
    • What does the first graph represent in the context of reaction rates?
      Volume of carbon dioxide produced
    • What does the second graph represent in the context of reaction rates?
      Mass being lost
    • How do you find the rate of reaction at a specific point on a graph?
      By drawing a tangent at that point
    • What does the gradient of the tangent represent?
      The rate of reaction at that point
    • How do you calculate the gradient of a tangent?
      Change in y divided by change in x
    • How does the steepness of the tangent relate to the rate of reaction?
      Steeper tangents indicate faster reactions
    • What are the indicators of a color change in a reaction?
      • Change from clear to opaque
      • Change in color intensity
    • What reaction is used to demonstrate color change?
      Between sodium thiosulfate and hydrochloric acid
    • What precautions should be taken during the sodium thiosulfate reaction?
      Wash equipment and avoid high temperatures
    • Why should the same person measure the rate of reaction?
      To ensure consistent results
    • What is a potential error when collecting gas in a measuring cylinder?
      Gas already present in the cylinder
    • What happens when powdered calcium carbonate is used instead of large marble chips?
      The reaction occurs much faster
    • How does temperature affect the rate of reaction?
      Higher temperatures increase reaction rates
    • What happens to sugar cubes in hot water compared to cold water?
      They dissolve faster in hot water
    • What is the relationship between surface area and reaction rate?
      Larger surface area increases reaction rate
    • How does spreading out a substance affect its drying time?
      It dries faster due to larger surface area
    • What factors affect the rate of reaction?
      • Temperature
      • Surface area
      • Concentration
      • Pressure
      • Presence of a catalyst
    • How does concentration affect the rate of reaction?
      Higher concentration increases reaction rate
    • What is the role of a catalyst in a reaction?
      It lowers the activation energy
    • What is activation energy?
      The energy needed to start a reaction
    • How does a catalyst affect the activation energy barrier?
      It lowers the activation energy barrier
    • What are the characteristics of endothermic and exothermic reactions?
      • Endothermic: absorbs energy, feels colder
      • Exothermic: releases energy, feels hotter
    • What happens to energy during an endothermic reaction?
      Energy is absorbed from the surroundings
    • What happens to energy during an exothermic reaction?
      Energy is released into the surroundings
    • How do you calculate energy change in a reaction?
      By considering bond energies
    • What is the balanced equation for burning hydrogen in oxygen?
      2H₂ + O₂ → 2H₂O
    • What bonds are present in the reaction of hydrogen and oxygen?
      Hydrogen-hydrogen, oxygen-oxygen, and oxygen-hydrogen bonds
    • How do you calculate the total bond energy on the reactants' side?
      Add the bond energies of all bonds
    • What is the energy change for the reaction of hydrogen and oxygen?
      -486 kJ/mol indicates exothermic
    • What does a negative energy change indicate?
      The reaction is exothermic
    • What should you practice for the exam regarding energy changes?
      Calculating energy changes in reactions
    • What is the significance of practicing calculations for the exam?
      It prepares you for likely exam questions
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