thermochemistry quiz high school

🧪 Quick Study Guide

• 🔥 Enthalpy (H): A measure of the total heat content of a system at constant pressure.
• 🌡️ Exothermic Reactions: Reactions that release heat to the surroundings ($\Delta H < 0$). Think burning wood!
• ❄️ Endothermic Reactions: Reactions that absorb heat from the surroundings ($\Delta H > 0$). Like melting ice.
• ⚖️ Hess's Law: The enthalpy change of a reaction is independent of the pathway taken. Allows us to calculate enthalpy changes using known values: $\Delta H_{reaction} = \sum \Delta H_{products} - \sum \Delta H_{reactants}$
• 📐 Calorimetry: The process of measuring the heat of chemical reactions or physical changes. We use the formula: $q = mc\Delta T$, where:
  • $q$ is heat transferred
  • $m$ is mass
  • $c$ is specific heat capacity
  • $\Delta T$ is the change in temperature
• 🎯 Standard Enthalpy of Formation ($\Delta H_f^\circ$): The enthalpy change when one mole of a compound is formed from its elements in their standard states (usually 298 K and 1 atm).

Practice Quiz

1. Which of the following describes an endothermic reaction?
   1. A) Releases heat to the surroundings.
   2. B) Absorbs heat from the surroundings.
   3. C) Has a negative \(\Delta H\) value.
   4. D) Causes the temperature of the surroundings to increase.
2. What is the symbol for enthalpy?
   1. A) E
   2. B) G
   3. C) H
   4. D) S
3. According to Hess's Law, the enthalpy change of a reaction:
   1. A) Depends on the pathway taken.
   2. B) Is independent of the pathway taken.
   3. C) Can only be measured directly.
   4. D) Is always positive.
4. What does a negative \(\Delta H\) indicate?
   1. A) An endothermic reaction.
   2. B) An exothermic reaction.
   3. C) No heat change.
   4. D) A change in entropy.
5. Which of the following is the correct formula for calculating heat transfer (q)?
   1. A) \(q = mc/\Delta T\)
   2. B) \(q = m\Delta T/c\)
   3. C) \(q = mc\Delta T\)
   4. D) \(q = m/c\Delta T\)
6. What is the standard state condition usually used for thermodynamic calculations?
   1. A) 0 K and 1 atm
   2. B) 273 K and 10 atm
   3. C) 298 K and 1 atm
   4. D) 300 K and 2 atm
7. In calorimetry, what does 'c' represent in the equation \(q = mc\Delta T\)?
   1. A) Molar heat capacity
   2. B) Specific heat capacity
   3. C) Heat of fusion
   4. D) Heat of vaporization