Topic 5- energy changes

• What happens to energy during chemical reactions?

  Energy is conserved.
• What does it mean that energy is conserved in reactions?

  The total energy remains constant throughout.
• What happens to product molecules in an exothermic reaction?

  They have less energy than the reactants.
• What is an exothermic reaction?

  It transfers energy to the surroundings.
• What is the effect of an exothermic reaction on surrounding temperature?

  The temperature of the surroundings increases.
• What is an endothermic reaction?

  It takes in energy from the surroundings.
• What happens to the temperature of surroundings during an endothermic reaction?

  The temperature of the surroundings decreases.
• What is a common use of endothermic reactions?

  Sports injury packs.
• What is required for chemical reactions to occur?

  Reacting particles must collide with sufficient energy.
• What is activation energy?

  Minimum energy needed for particles to react.
• How can reaction profiles be used?

  To show relative energies of reactants and products.
• How can you determine if a reaction is exothermic or endothermic from a reaction profile?

  By comparing the energy levels of reactants and products.

  
• What indicates an exothermic reaction on a reaction profile?

  Products have less energy than reactants.
• What indicates an endothermic reaction on a reaction profile?

  Products have more energy than reactants.
• What happens to energy during a chemical reaction when bonds are broken?

  Energy must be supplied to break bonds.
• What happens when bonds in products are formed?

  Energy is released when bonds are formed.
• How can overall energy change be calculated in a reaction?

  Sum of energy to break bonds minus energy to form bonds.
• What characterizes an endothermic reaction in terms of energy?

  More energy is taken in to break bonds.
• What characterizes an exothermic reaction in terms of energy?

  Less energy is taken in to break bonds.