8.1.1 Standard Enthalpy Changes

• What is the standard enthalpy change (ΔH°)?

  Change in enthalpy under standard conditions
• The standard enthalpy change is measured under standard conditions, which include a temperature of 298 K and a pressure of 1 atm.
• The standard enthalpy change is expressed in kJ/mol.
• What is the standard enthalpy of formation (ΔH°f)?

  Enthalpy change when 1 mole of a compound is formed from its elements
• The standard enthalpy of combustion (ΔH°c) is the enthalpy change when 1 mole of a substance is completely burned in oxygen.
• What does the standard enthalpy of reaction (ΔH°r) measure?

  Enthalpy change for a reaction under standard conditions
• Standard conditions include a temperature of298 K and a pressure of 101.3 kPa.
• Match the standard condition with its value:

  Temperature ↔️ 298 K

  Pressure ↔️ 1 atm
• Give an example of a reaction for the standard enthalpy of formation (ΔH°f).

  H₂(g) + ½ O₂(g) → H₂O(l)
• What is an example of a reaction for the standard enthalpy of combustion (ΔH°c)?

  CH₄(g) + 2O₂(g) → CO₂(g) + 2H₂O(l)
• What is an example of a reaction for the standard enthalpy of reaction (ΔH°r)?

  2H₂(g) + O₂(g) → 2H₂O(l)
• Standard conditions and STP have the same temperature and pressure.

  False
• What is the temperature in Kelvin for STP?

  273 K
• The standard enthalpy of formation for water (H₂O) is -286 kJ/mol.
• What is the standard enthalpy of formation for liquid water (H₂O)?

  -286 kJ/mol
• Standard conditions for enthalpy changes are defined as 298 K and 1 atm
• The standard temperature for enthalpy changes is 25°C.
• What is the key difference between standard conditions and STP in terms of temperature?

  298 K vs. 273 K
• The standard enthalpy of formation is the enthalpy change when 1 mole of a compound is formed from its elements
• What is the symbol for the standard enthalpy of combustion?

  ΔH°c
• The standard enthalpy of formation is expressed in kJ/mol.
• The standard enthalpy of combustion is measured when 1 mole of a substance is completely burned in oxygen
• What is the standard enthalpy of combustion for methane (CH₄)?

  -890 kJ/mol
• The standard enthalpy of combustion is always exothermic.
• What is the standard enthalpy of combustion for methane (CH₄)?

  -890 kJ/mol
• The standard enthalpy of neutralization is the enthalpy change when 1 mole of water is formed by the complete neutralization of an acid and a base
• What is the standard enthalpy of neutralization for HCl with NaOH?

  -57.2 kJ/mol
• The standard enthalpy of neutralization is expressed in kJ/mol.
• The standard enthalpy change is the change in enthalpy when a reaction occurs under standard conditions
• What is the standard enthalpy change for the formation of water (H₂O)?

  -286 kJ/mol
• Match the term with its definition under standard conditions:

  Temperature ↔️ 298 K (25°C)

  Pressure ↔️ 1 atm (101.3 kPa)
• What temperature is specified under standard conditions in Kelvin?

  298 K
• The standard pressure under standard conditions is 1 atm
• Standard conditions and standard temperature and pressure (STP) use the same temperature.

  False
• What is the standard temperature in degrees Celsius under standard conditions?

  25°C
• Match the standard conditions with their values:

  Standard Temperature ↔️ 298 K

  Standard Pressure ↔️ 1 atm
• What is the standard enthalpy of formation for water (H₂O) under standard conditions in kJ/mol?

  -286 kJ/mol
• The standard enthalpy of formation is the enthalpy change when 1 mole of a compound is formed from its elements in their standard states.
• What is the definition of the standard enthalpy of combustion?

  Complete combustion of 1 mole
• Match the type of enthalpy change with its symbol:

  Standard Enthalpy of Formation ↔️ ΔH°f

  Standard Enthalpy of Combustion ↔️ ΔH°c

  Standard Enthalpy of Neutralization ↔️ ΔH°neut