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Quiz Chapter 5: Thermochemistry

10 questions ยท Form 3 Science Bab 5: Thermochemistry

Question 1 of 10Score: 0

How does the total energy content of reactants compare to products in an exothermic reaction?

Full Question List & Answer Key

Prefer reading to quizzing? All 10 questions are listed below with the answer and explanation under each one.

1. How does the total energy content of reactants compare to products in an exothermic reaction?

  1. Total energy of reactants is higher than products
  2. Total energy of reactants is lower than products
  3. Total energy of reactants and products are equal
  4. Reactants have zero energy content
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Answer: A

In exothermic reactions, reactants hold higher chemical potential energy than products; the difference is released as heat energy.

2. What primary branch of science studies heat energy changes during chemical reactions?

  1. Electrochemistry
  2. Thermochemistry
  3. Biochemistry
  4. Organic Chemistry
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Answer: B

Thermochemistry is the scientific branch specifically focused on heat energy absorbed or released during chemical changes.

3. Which application is suitable for treating an athlete's acute muscle sprain on the field?

  1. Instant hot pack to increase swelling
  2. Instant cold pack to reduce pain and swelling
  3. Rubbing ethanol to burn the skin surface
  4. Applying baking soda and vinegar
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Answer: B

Instant cold packs absorb heat, constricting blood vessels and helping to reduce pain and swelling in acute sports injuries.

4. Which chemical compound is commonly used in instant hot packs?

  1. Ammonium nitrate
  2. Ammonium chloride
  3. Anhydrous calcium chloride
  4. Potassium nitrate
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Answer: C

Anhydrous calcium chloride dissolves in water exothermically, releasing heat energy which makes it suitable for instant hot packs.

5. When solid sodium hydroxide pellets ($NaOH$) are dissolved in distilled water, what is observed regarding the container temperature?

  1. The container becomes noticeably hotter
  2. The container becomes noticeably colder
  3. The container freezes into ice
  4. No temperature change occurs
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Answer: A

Dissolving sodium hydroxide in water releases a significant amount of heat energy (exothermic process), making the container hot.

6. In a laboratory experiment investigating heat changes, why are polystyrene cups often used as reaction vessels instead of glass beakers?

  1. Polystyrene is a good heat conductor
  2. Polystyrene is a good thermal insulator that minimizes heat loss or gain to surroundings
  3. Polystyrene reacts with acid to give a clearer color
  4. Polystyrene increases the speed of chemical reactions
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Answer: B

Polystyrene acts as an insulator, reducing heat exchange with the external surroundings to ensure accurate temperature change measurements.

7. Which chemical compound is typically present in instant cold packs used to reduce muscle swelling?

  1. Sodium hydroxide
  2. Ammonium nitrate
  3. Calcium oxide
  4. Magnesium ribbon
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Answer: B

Dissolving ammonium nitrate in water is an endothermic process that rapidly absorbs heat from its surroundings, cooling the pack down.

8. What happens to the temperature of the surroundings during an exothermic reaction?

  1. It decreases
  2. It increases
  3. It remains constant
  4. It fluctuates unpredictably
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Answer: B

In an exothermic reaction, heat is released into the surroundings, causing the temperature of the surroundings to increase.

9. What happens to energy when chemical bonds are formed during a chemical reaction?

  1. Energy is absorbed
  2. Energy is released
  3. Energy remains unaffected
  4. Energy is completely destroyed
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Answer: B

Bond breaking absorbs energy (endothermic step), whereas bond formation releases energy (exothermic step).

10. Which instrument is used to measure the temperature change during a thermochemical experiment in a school laboratory?

  1. Barometer
  2. Thermometer
  3. Anemometer
  4. Hydrometer
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Answer: B

A thermometer measures the temperature of the reaction mixture or surroundings to detect thermal changes.

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