Question 1

The following can be used to measure the heat of combustion for an unknown sample? Outcome # 10) DOK 2)&#10;A) bomb manometer&#10;B) bomb calorimeter&#10;C) coffee-cup calorimeter

Accepted Answer

A bomb calorimeter is specifically designed to measure the heat of combustion of a sample by containing the reaction in a strong, sealed container and measuring the temperature change of the surrounding water bath.

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

Accepted Answer

The combustion of methane can be represented by the equation: CH₄(g) + 2O₂(g) → CO₂(g) + 2H₂O(l). Using Hess's Law, ∆H°rxn = ∑∆H°f(products) - ∑∆H°f(reactants). For products, it's (-393.5 kJ/mol for CO₂ + 2(-285.8 kJ/mol) for 2H₂O) and for reactants, it's -74.6 kJ/mol for CH₄ (O₂ is a standard state element with ∆H°f = 0). Thus, ∆H°rxn = (-393.5 - 2*285.8) - (-74.6) = -890.5 kJ/mol.

Question 3

Coffee-cup calorimetry is carried out at _____. Outcome # 10) DOK 1)&#10;A) constant-volume&#10;B) constant-pressure&#10;C) constant-mass

Accepted Answer

Coffee-cup calorimetry is performed at constant pressure, allowing the system to exchange heat with its surroundings at atmospheric pressure.

Question 4

If &#8710;H = -73.54 kJ for a chemical reaction, that reaction _____________. Outcome # 1,5,9) DOK 2)&#10;A) is exothermic&#10;B) is endothermic&#10;C) cannot occur

Accepted Answer

An exothermic reaction releases heat, indicated by a negative ∆H value.

Question 5

A chemical reaction that absorbs energy in the form of heat is considered _____. Outcome # 5) DOK 2) Paired item 1)&#10;A) exothermic&#10;B) endothermic&#10;C) exergonic

Accepted Answer

Endothermic reactions absorb energy from their surroundings, typically in the form of heat.

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)&#10;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.&#10;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.&#10;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.

Accepted Answer

Boiling water is an endothermic process because it requires the absorption of heat to break the intermolecular forces that hold water molecules together. The positive sign in +40.7 kJ indicates that energy is absorbed, not released.

Question 7

A reaction where the products are lower in energy than the reactants is an example of an _____. Outcome # 6) DOK 1)&#10;A) endothermic process&#10;B) exothermic process&#10;C) endergonic process

Accepted Answer

An exothermic process releases energy in the form of heat, and because the products are lower in energy than the reactants, this is the most appropriate choice. Endothermic processes, in contrast, absorb heat and have products that are higher in energy than the reactants. Endergonic processes involve the input of energy, but do not necessarily result in products that are lower in energy than the reactants.

Question 8

Bomb calorimetry is carried out at _____. Outcome # 10) DOK 1)&#10;A) constant-volume&#10;B) constant-pressure&#10;C) constant-mass

Accepted Answer

Bomb calorimetry is performed at constant volume, which allows for the accurate measurement of heat released or absorbed during a reaction.

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

Accepted Answer

The formation of diamond from graphite can be considered as a reaction where graphite is converted into diamond. Given that the enthalpy of formation (∆H°f) for graphite is 0 kJ/mol and for diamond is 2 kJ/mol, the reaction enthalpy (∆H°rxn) is simply the difference in the enthalpy of formation of the products and reactants. Since graphite is the reactant and its ∆H°f is 0, and diamond is the product with a ∆H°f of 2 kJ/mol, the ∆H°rxn for the formation of diamond from graphite is +2 kJ/mol.

Question 10

If &#916;H = -54.74 kJ for a chemical reaction, that reaction _____________. Outcome # 1,2) DOK 1&#10;A) is exothermic&#10;B) is endothermic&#10;C) cannot occur

Accepted Answer

An exothermic reaction releases heat, indicated by a negative ΔH value.

Question 11

A reaction where the products are higher in energy than the reactants is an example of an _____. Outcome # 6) DOK 1)&#10;A) endothermic process&#10;B) exothermic process&#10;C) exergonic process

Accepted Answer

The answer of A reaction where the products are higher...

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.

Accepted Answer

The answer of A drop in water temperature is observed...

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.

Accepted Answer

The answer of An increase in water temperature is observed...

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)&#10;A) manometer&#10;B) thermometer&#10;C) calorimeter

Accepted Answer

The answer of A _____ is an experimental set-up that...

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

Accepted Answer

The answer of You are asked to design an experiment...

Question 16

A chemical reaction that gives off energy in the form of heat is considered _____. Outcome # 5) DOK 2)&#10;A) exothermic&#10;B) endothermic&#10;C) exergonic

Accepted Answer

The answer of A chemical reaction that gives off energy...

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)&#10;A) exergonic&#10;B) endothermic&#10;C) exothermic

Accepted Answer

The answer of An _____ reaction results when the energy...

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)&#10;A) exergonic&#10;B) endothermic&#10;C) exothermic

Accepted Answer

The answer of An _____ reaction results when the energy...

Deck 5: Thermochemistry