Thermochem Review Bellringer

The standard enthalpy of formation for nitrogen dioxide is the enthalpy change of the reaction

• 1/2 N₂(g) + O₂(g) --> NO₂(g)

• N₂ (g) + 2 O₂(g) --> N₂O₄ (g)

• N₂(g) +2 O₂(g) --> 2 NO₂(g)

• NO(g) + 1/2 O₂(g) --> NO₂(g)

Which of the following has a non-zero standard enthalpy of formation?

• Na (s)

• Hg (l)

• H₂O (l)

• N2 (g)

For endothermic reactions at constant pressure

• ΔH < 0

• ΔH > 0

• ΔH = 0

• ΔH = negative

The enthalpy of reaction between HCl and NaOH is to be determined by a calorimetry experiment. The solutions are combined in an insulated container that is isolated from the environment.

Which data must be collected to calculate the enthalpy of reaction?

• volume, pressure, initial and final temperature

• conductivity, concentration, pH

• initial and final temperature, absorbance, concentration

• concentration, volume, initial and final temperature

The enthalpy of reaction between HCl and NaOH is to be determined by a calorimetry experiment. The solutions are combined in an insulated container that is isolated from the environment.

How does the temperature change and why does it occur?

• The temperature increases due to friction of mixing.

• The temperature decreases because water is formed in the reaction, and it has a high specific heat.

• The temperature decreases due to decrease in entropy from the formation of a salt.

• The temperature increases because potential energy of the chemical bonds is released as thermal energy.