Thermochemistry - honors chem

The units for heat capacity (C) are:

• J/℃

• J/(g⋅℃)

• g/J

• g/(J⋅℃)

Acetylene, C₂H₂, is a gas used in welding. The molar enthalpy of combustion for acetylene is –2599 kJ. A mass of 0.338 g C₂H₂(g) is combusted in a bomb calorimeter. If the heat capacity of the calorimeter is 5.54 kJ/°C, what is the temperature increase of the bomb calorimeter?

• 18.0°C

• 12.3°C

• 7.01°C

• 6.09°C

• 1.59°C

Tags

NGSS.HS-PS1-4

NGSS.HS-PS3-4

The enthalpy of formation is the change in enthalpy when a compound is made from its constituent:

• mixture

• electrons

• elements

• molecules

Tags

NGSS.HS-PS1-4

Commercial cold packs consist of solid ammonium nitrate and water. NH₄NO₃ absorbs 25.69 kJ of heat per mole dissolved in water. In a coffee-cup calorimeter, 5.60 g NH₄NO₃ is dissolved in 100.0 g of water at 22.0°C. What is the final temperature of the solution? Assume that the solution has a specific heat capacity of 4.18 J/g⋅°C.

• 0.0°C

• 17.9°C

• 11.6°C

• 26.1°C

• –54.8°C

Tags

NGSS.HS-PS1-4

NGSS.HS-PS3-4

What is the enthalpy of reaction for the following reaction:

Fe₂O₃(s) + 3CO(g) ⟶ 2Fe(s) + 3CO₂(g)

ΔH_f of each term is as follows:

Fe₂O₃(s) = -824.2kJ

CO(g) = -110.5kJ (be sure to multiply by coefficient)

Fe(s) = 0kJ

CO₂(g) = -393.5kJ (multiply also)

• +23.5kJ

• -23.5kJ

• -541.2kJ

• +541.2kJ

Tags

NGSS.HS-PS1-4

NGSS.HS-PS3-1