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Unit Quiz: Energy changes (HT)

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Q1. What is the minimum amount of energy needed to start a reaction?

Options:

  1. Activation energy
  2. Kinetic energy
  3. Thermal energy

Correct Answer:

  1. Activation energy

Q2. What type of reaction does this energy level diagram represent?

Options:

  1. Exothermic reaction
  2. Endothermic reaction
  3. Fast reaction
  4. Slow reaction

Correct Answer:

  1. Endothermic reaction

Q3. A reaction is overall endothermic because...

Options:

  1. More energy has been taken in than has been released
  2. More energy has been released than has been taken in
  3. More bonds have been broken
  4. More bonds have been made

Correct Answer:

  1. More energy has been taken in than has been released

Q4. To break a C-C bond it requires 348 kJ/mol of energy, how much energy is released when a C-C bond is made?

Options:

  1. 242 kJ/mol
  2. 348 kJ/mol
  3. 174 kJ/mol
  4. 696 kJ/mol

Correct Answer:

  1. 348 kJ/mol

Q5. What happens to bonds during a chemical reaction?

Options:

  1. Nothing they stay the same
  2. Bonds are broken
  3. Bonds are made
  4. Bonds are broken and made.

Correct Answer:

  1. Bonds are broken and made.

Q6. Which arrow in the energy level diagram represents activation energy?

Options:

  1. A
  2. B
  3. C
  4. None of the above

Correct Answer:

  1. A

Q7. Which arrow in the energy level represents the overall energy change?

Options:

  1. A
  2. B
  3. C
  4. None of the above

Correct Answer:

  1. B

Q8. What type of reaction is shown in the energy level diagram?

Options:

  1. Endothermic
  2. Exothermic
  3. None of the above

Correct Answer:

  1. Exothermic

Q9. If the overall energy change is negative, what type of reaction is it?

Options:

  1. Endothermic
  2. Exothermic
  3. None of the above

Correct Answer:

  1. Exothermic

Q10. During a reaction, 2462 kJ/mol of energy is needed to break bonds and 1363 kJ/mol of energy is released when bonds are made. What type of reaction is it?

Options:

  1. Exothermic, because more energy was released than was absorbed
  2. Endothermic, because more energy was released than was absorbed
  3. Exothermic, because more energy was taken in than was released
  4. Endothermic, because more energy was taken in than was released

Correct Answer:

  1. Endothermic, because more energy was taken in than was released

Q11. During a reaction 988 kJ/mol of energy is needed to break bonds and 1892 kJ/mol of energy is released when bond are made. What type of reaction is it?

Options:

  1. Exothermic, because more energy was released than was absorbed
  2. Endothermic, because more energy was released than was absorbed
  3. Exothermic, because more energy was taken in than was released
  4. Endothermic, because more energy was taken in than was released

Correct Answer:

  1. Exothermic, because more energy was released than was absorbed

Q12. A student is investigating the effect of changing the concentration of acid on the temperature change when reacting an acid with an alkali. Identify the independent variable.

Options:

  1. Concentration of acid
  2. Volume of acid
  3. Volume of alkali
  4. Concentration of alkali

Correct Answer:

  1. Concentration of acid

Q13. What happens to the temperature of the surroundings when an exothermic reaction occurs?

Options:

  1. The temperature increases
  2. The temperature decreses
  3. Energy is given out to the surroundings
  4. Energy is taken in from the surroundings

Correct Answer:

  1. The temperature increases

Q14. Why is it important to use a polystyrene cup in an experiment where the temperature change is measured?

Options:

  1. So it doesn't spill
  2. To reduce the energy transfer to the surroundings
  3. To make it a fair test

Correct Answer:

  1. To reduce the energy transfer to the surroundings

Q15. Why is it important to do at least 3 repeats?

Options:

  1. To make it a fair test
  2. To make it accurate
  3. To identify anomalies and calculate a mean
  4. To make the results more precise

Correct Answer:

  1. To identify anomalies and calculate a mean

Q16. Select 4 examples of exothermic reactions:

Options:

  1. Combustion
  2. Respiration
  3. Photosynthesis
  4. Neutralisation
  5. Thermal decomposition
  6. Oxidation

Correct Answer:

  1. Combustion
  2. Respiration
  3. Neutralisation
  4. Oxidation

Q17. What measurement could we take to determine if a reaction was endothermic or exothermic?

Options:

  1. The mass change, using a balance
  2. The volume change, using a gas syringe
  3. The temperature change, using a thermometer
  4. The energy change, using a thermometer

Correct Answer:

  1. The temperature change, using a thermometer

Q18. Hypothesis: A student investigated the temperature change when zinc reacts with different concentrations of copper sulfate. What is the independent variable?

Options:

  1. The concentration of copper sulfate
  2. The volume of copper sulfate
  3. The mass of the zinc
  4. The size of the zinc

Correct Answer:

  1. The concentration of copper sulfate

Q19. Hypothesis: A student investigated the temperature change when zinc reacts with different concentrations of copper sulfate? What is the dependent variable?

Options:

  1. The volume of copper sulfate
  2. The temperature change
  3. The colour change
  4. The mass of the zinc

Correct Answer:

  1. The temperature change

Q20. Hypothesis: A student investigated the temperature change when zinc reacts with different concentrations of copper sulfate. What are the control variables? Choose 2 answers.

Options:

  1. The volume of the copper sulfate
  2. The starting temperature of the copper sulfate
  3. Concentration of the copper sulfate
  4. The mass of the zinc
  5. The temperature change

Correct Answer:

  1. The volume of the copper sulfate
  2. The mass of the zinc