Deck 5: Thermochemistry

Question 1

The following can be used to measure the heat of combustion for an unknown sample? Outcome # 10) DOK 2)

A) bomb manometer
B) bomb calorimeter
C) coffee-cup calorimeter

Answer 1

bomb calorimeter

Question 2

Calculate the ∆H°_rxn for the combustion of methane using the given ∆H°_f. Outcome # 11) DOK 3) ∆H°_f, methaneg) = -74.60 kJ/mol
∆H°_f, waterl) = -285.8 kJ/mol
∆H°_f, carbon dioxideg) = -393.5 kJ/mol

A) -1.04 x 10⁺³ kJ/mol
B) -890.5 kJ/mol
C) 890.5 kJ/mol

Answer 2

-890.5 kJ/mol

Question 3

Coffee-cup calorimetry is carried out at _____. Outcome # 10) DOK 1)

A) constant-volume
B) constant-pressure
C) constant-mass

Answer 3

constant-pressure

Question 4

If ∆H = -73.54 kJ for a chemical reaction, that reaction _____________. Outcome # 1,5,9) DOK 2)

A) is exothermic
B) is endothermic
C) cannot occur

Question 5

A chemical reaction that absorbs energy in the form of heat is considered _____. Outcome # 5) DOK 2) Paired item 1)

A) exothermic
B) endothermic
C) exergonic

Question 6

A reaction requires a sample to be heated using a water bath near boiling temperature. Which statement below would be accurate? Outcome # 5) DOK 3)

A) Boiling water is an endothermic process and to break apart the intermolecular forces that hold together the water molecules requires -40.7 kJ of energy.
B) Boiling water is an exothermic process and to break apart the intermolecular forces that hold together the water molecules requires +40.7 kJ of energy.
C) Boiling water is an endothermic process and to break apart the intermolecular forces that hold together the water molecules requires +40.7 kJ of energy.

Question 7

A reaction where the products are lower in energy than the reactants is an example of an _____. Outcome # 6) DOK 1)

A) endothermic process
B) exothermic process
C) endergonic process

Question 8

Bomb calorimetry is carried out at _____. Outcome # 10) DOK 1)

A) constant-volume
B) constant-pressure
C) constant-mass

Question 9

Given the ∆H°_f, calculate the ∆H°_rxn for the formation of diamond from graphite. Outcome # 11) DOK 2) ∆H°_f C, graphite) = 0 kJ/mol
∆H°_f C, diamond) = 2 kJ/mol

A) 0 kJ/mol
B) +2 kJ/mol
C) -2 kJ/mol

Question 10

If ΔH = -54.74 kJ for a chemical reaction, that reaction _____________. Outcome # 1,2) DOK 1

A) is exothermic
B) is endothermic
C) cannot occur

Question 11

A reaction where the products are higher in energy than the reactants is an example of an _____. Outcome # 6) DOK 1)

A) endothermic process
B) exothermic process
C) exergonic process

Question 12

A drop in water temperature is observed when 0.873 g of ammonium nitrate is added. The enthalpy change for this reaction is +0.280 kJ. Which of the statements is accurate? Outcome # 11) DOK 3)

A) The ∆H°_soln for ammonium nitrate is +25.7 kJ/mol so this is an endothermic process where energy in the form of heat is absorbed from the surroundings.
B) The ∆H°_soln for ammonium nitrate is -25.7 kJ/mol so this is an exothermic process where energy in the form of heat is released into the surroundings.
C) The ∆H°_soln for ammonium nitrate is +25.7 kJ/mol so this is an endothermic process where energy in the form of heat is released into the surroundings.

Question 13

An increase in water temperature is observed when 1.97 g of NaOH is added. The enthalpy change for this reaction is -2.19 kJ. Which of the statements is accurate? Outcome # 11) DOK 3) Paired item 1)

A) The ∆H°_soln for NaOH is +44.5 kJ/mol so this is an endothermic process where energy in the form of heat is absorbed from the surroundings.
B) The ∆H°_soln for NaOH is -44.5 kJ/mol so this is an exothermic process where energy in the form of heat is released into the surroundings.
C) The ∆H°_soln for NaOH is -44.5 kJ/mol so this is an exothermic process where energy in the form of heat is absorbed from the surroundings.

Question 14

A _____ is an experimental set-up that can be used to measure the heat of a chemical reaction or a physical change and determine the specific heat capacity of a substance. Outcome # 10) DOK 1)

A) manometer
B) thermometer
C) calorimeter

Question 15

You are asked to design an experiment to measure the enthalpy of a given reaction. The reaction needs to be at atmospheric pressure so which of the following techniques would be ideal for this experiment? Outcome # 10) DOK 3)

A) bomb manometry
B) bomb calorimetry
C) coffee-cup calorimetry

Question 16

A chemical reaction that gives off energy in the form of heat is considered _____. Outcome # 5) DOK 2)

A) exothermic
B) endothermic
C) exergonic

Question 17

An _____ reaction results when the energy required to break bonds in the reactants is greater than the energy released by the formation of products. Outcome # 3) DOK 1)

A) exergonic
B) endothermic
C) exothermic

Question 18

An _____ reaction results when the energy released by the formation of products is greater than the energy required to break the bonds in the reactants. Outcome # 3) DOK 1)

A) exergonic
B) endothermic
C) exothermic