Quiz Chapter 5: Thermochemistry

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

2. A student mixes baking soda with vinegar in a cup and notices the temperature drops from 28°C to 21°C. What can be concluded?

1. The reaction is exothermic because heat is generated
2. The reaction is endothermic because heat is absorbed from the solution
3. The reaction destroyed energy entirely
4. The mixture undergoes physical condensation

3. Which statement correctly describes heat flow during an endothermic reaction?

1. Heat flows from the reaction mixture to the surroundings
2. Heat flows from the surroundings into the reaction mixture
3. There is no heat flow between system and surroundings
4. Heat flows only inside the nuclei of atoms

4. Which of the following daily phenomena involves an exothermic chemical reaction?

1. Baking a cake in an oven
2. Evaporation of sweat from skin
3. Burning a candle
4. Thermal decomposition of limestone

5. Why does cellular respiration count as an exothermic reaction?

1. It absorbs carbon dioxide and heat from the environment
2. It breaks down glucose to release energy for body activities
3. It requires sun light to break chemical bonds in blood
4. It converts heat energy into solid carbohydrates

6. 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

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

1. Ammonium nitrate
2. Ammonium chloride
3. Anhydrous calcium chloride
4. Potassium nitrate

8. 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

9. 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

10. 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