Enthalpy Change in rate of H of a Reaction - Reaction Enthalpy

What is the formula for calculating reaction enthalpy?

• Sum of enthalpies of products plus sum of enthalpies of reactants

• Sum of enthalpies of products minus sum of enthalpies of reactants

• Sum of enthalpies of reactants minus sum of enthalpies of products

• Sum of enthalpies of reactants plus sum of enthalpies of products

What does the standard state of a substance refer to?

• Its pure form at 1 atm and any temperature

• Its pure form at 1 bar and any temperature

• Its pure form at 1 bar and 298 Kelvin

• Its pure form at 1 atm and 273 Kelvin

Which of the following is true about the enthalpy of fusion?

• It is always positive

• It is zero

• It is always negative

• It can be either positive or negative

Which process requires heat at constant pressure and a constant boiling temperature?

• Vaporization

• Condensation

• Sublimation

• Fusion

What is the enthalpy change called when a solid directly converts into vapor?

• Enthalpy of condensation

• Enthalpy of fusion

• Enthalpy of vaporization

• Enthalpy of sublimation

What is the standard enthalpy of formation for an element in its standard state?

• It is zero

• It is always negative

• It is always positive

• It can be either positive or negative

What is the standard enthalpy of formation for a compound formed from its elements in their standard states?

• Delta rH theta

• Delta fH theta

• Delta sH theta

• Delta cH theta

How is the enthalpy change of a reaction affected when the reaction is reversed?

• It remains the same

• It is halved

• It changes sign

• It doubles

What is the significance of stoichiometric coefficients in thermochemical equations?

• They refer to the number of molecules

• They refer to the number of moles

• They refer to the number of ions

• They refer to the number of atoms

What happens to the value of delta rH theta when a chemical reaction is balanced differently?

• It doubles

• It becomes zero

• It changes

• It remains unchanged