Quiz: Enthalpy

1. The difference in the heat contents of the products and the reactants is called
a. temperature
b. heat of a reaction
c. heat of calorimetry
2. The heat of a given reaction is called the change in
a. enthalpy
b. entropy
c. free energy
3. The change in enthalpy is the change in heat energy of a reaction and is calculated by
a. Σ(heat content of the reactants) − Σ(heat content of the products)
b. Σ(heat content of the products) − Σ(heat content of the reactants)
c. heat content of products × heat content of the reactants
4. If the reaction is endothermic, the sign of Δ H will be
a. negative
b. neutral
c. positive
5. Standard enthalpies occur at what set of conditions?
a. 25°C and 1.0 atm
b. 100°C and 1.0 atm
c. 25°C and 2.0 atm
6. The standard enthalpy for an element in its reference form is defined as
a. –2.0 kJ/mol
b. 0 kJ/mol
c. 2.0 kJ/mol
7. When looking up enthalpy values for a set of reaction species, the enthalpy depends on the
a. physical state of the species
b. color of the species
c. concentration of the species
8. If the Δ H of a reaction is negative, the reaction is
a. endothermic and releasing heat
b. exothermic and releasing heat
c. exothermic and absorbing heat
9. When 1.0 mole of ZnO( s) decomposes, the Δ H = 348 kJ/mol of heat energy. What does this tell you about the formation of ZnO( s)?
a. the formation of ZnO( s) is endothermic
b. the formation of ZnO( s) does not require energy
c. the formation of ZnO( s) is exothermic
10. What is the Δ H value for O2( g)?
a. 142 kJ/mol
b. 0 kJ/mol
c. –142 kJ/mol

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