2.8 AS 2 Energetics

What are the standard conditions for measuring enthalpy changes?

• 100 kPa and 273 K

• 101 kPa and 298 K

• 100 kPa and 298 K

• 101 kPa and 273 K

Which term describes a chemical reaction that absorbs heat from its surroundings?

• Exothermic

• Endothermic

• Isothermic

• Thermodynamic

What is the equation used to calculate enthalpy changes from experimental data?

• q = mcΔT

• q = mΔT

• q = cΔT

• q = mT

What does Hess's Law help to determine?

• The rate of a chemical reaction

• The equilibrium constant of a reaction

• The enthalpy change of a reaction

• The activation energy of a reaction

What is the term for the heat change at constant pressure?

• Entropy

• Enthalpy

• Energy

• Exergy

What is the standard enthalpy change of formation denoted as?

• ΔHf°

• ΔHc°

• ΔHr°

• ΔHn°

Which of the following statements is true about an endothermic reaction?

• The enthalpy of the products is less than the enthalpy of the reactants.

• The enthalpy of the products is greater than the enthalpy of the reactants.

• The enthalpy of the products is equal to the enthalpy of the reactants.

• The enthalpy change has a negative sign.

Which of the following reactions represents the standard enthalpy change of combustion (ΔHc°)?

• C(s) + 2H2(g) → CH4(g)

• ½H2(g) + ½Cl2(g) → HCl(g)

• C2H5OH(l) + 3O2(g) → 2CO2(g) + 3H2O(l)

• HCl(aq) + NaOH(aq) → NaCl(aq) + H2O(l)

What is the activation energy (Ea) in a chemical reaction?

• The energy released during the reaction.

• The energy required to start the reaction.

• The energy difference between reactants and products.

• The energy absorbed by the products.

Which of the following statements is true about exothermic reactions?

• The enthalpy of the products is greater than the enthalpy of the reactants.

• The enthalpy of the products is less than the enthalpy of the reactants.

• The enthalpy change has a positive sign.

• The enthalpy change is zero.