Untitled Presentation

Multiple Choice

Which of the following best describes an exothermic reaction in thermochemistry?

• A reaction that absorbs heat from its surroundings

• A reaction that releases heat to its surroundings

• A reaction that does not involve any heat change

• A reaction that only occurs at high temperatures

Open Ended

Why is the study of thermochemistry important in understanding chemical reactions?

Multiple Choice

Which of the following best describes the main focus of thermochemistry?

• The study of chemical reactions without energy changes

• The study of energy changes, especially heat, during chemical and physical processes

• The study of the structure of atoms

• The study of environmental chemistry

Open Ended

Explain the difference between a system and its surroundings in the context of thermochemistry.

Multiple Choice

Which type of system does a thermos flask most closely represent?

• Open system

• Closed system

• Isolated system

• Dynamic system

Multiple Choice

Which of the following statements about open, closed, and isolated systems is correct?

• An open system allows exchange of both matter and energy with its surroundings.

• A closed system allows exchange of matter but not energy.

• An isolated system allows exchange of energy but not matter.

• All three systems allow exchange of both matter and energy.

Open Ended

Describe a real-life example of a closed system and explain why it is considered closed.

Multiple Choice

Which type of system does not allow the exchange of matter or energy with its surroundings?

• Open system

• Closed system

• Isolated system

• Thermal system

Open Ended

Explain the difference between an open, closed, and isolated system in terms of energy and matter exchange.

Multiple Choice

Based on the comparison table, which system allows the transfer of energy but not matter?

• Open system

• Closed system

• Isolated system

• Thermal system

Multiple Choice

Which processes in the diagram illustrate the law of conservation of energy in living systems?

• Photosynthesis and respiration

• Photosynthesis and mineral absorption

• Respiration and enthalpy change

• Mineral absorption and enthalpy change

Open Ended

Give an example from daily life where you obtain energy and another where you release energy.

Multiple Choice

Which statement best describes enthalpy (H) in a chemical system at constant pressure?

• It is the energy stored in a system and represented by the symbol H.

• It is the amount of heat released during a reaction.

• It is the energy lost to the surroundings.

• It is the temperature change during a reaction.

Open Ended

Explain how enthalpy change (ΔH) is calculated and what it represents in a chemical reaction.

Multiple Select

Which of the following statements are true about exothermic and endothermic reactions as illustrated in the diagram?

• Exothermic reactions release heat to the surroundings.

• Endothermic reactions absorb heat from the surroundings.

• Exothermic reactions result in a temperature increase in the surroundings.

• Endothermic reactions result in a temperature decrease in the surroundings.

Multiple Choice

Which of the following reactions is an example of an exothermic reaction?

• CaCO3(s) → CaO(s) + CO2(g)

• 3H2(g) + N2(g) → 2NH3(g)

• Lemon juice + baking soda

• Melting ice

Open Ended

Compare the direction of heat flow and the sign of ΔH in endothermic and exothermic reactions.

Multiple Choice

Which of the following statements correctly describes the difference between exothermic and endothermic reactions based on the energy diagrams?

• Exothermic reactions release energy, resulting in lower enthalpy of products compared to reactants, while endothermic reactions absorb energy, resulting in higher enthalpy of products compared to reactants.

• Exothermic reactions absorb energy, resulting in higher enthalpy of products compared to reactants, while endothermic reactions release energy, resulting in lower enthalpy of products compared to reactants.

• Both exothermic and endothermic reactions release energy, but the enthalpy of products is always higher than reactants.

• Both exothermic and endothermic reactions absorb energy, but the enthalpy of products is always lower than reactants.

Multiple Select

Which of the following experiments demonstrates an endothermic reaction?

• Mg + HCl (T1 = 25°C, T2 = 32°C)

• Urea + Water (T1 = 28°C, T2 = 16°C)

• Limestone + Water (T1 = 26°C, T2 = 30°C)

• Ba(OH)2·8H2O + Water (T1 = 27°C, T2 = -3°C)

Open Ended

Based on the experiments shown, explain how you can determine whether a reaction is exothermic or endothermic using temperature changes.

Multiple Choice

Which of the following is a characteristic of an exothermic reaction in thermochemistry?

• It absorbs heat from the surroundings

• It releases heat to the surroundings

• It involves a positive change in enthalpy (ΔH)

• It is always a combustion reaction

Open Ended

Reflecting on what you learned about thermochemistry, what is one concept you found most interesting or would like to explore further?