Question 1

Which one of the following is a correct formation reaction?

Accepted Answer

A) C(diamond) $\to$ C(graphite) 
B) H2(g)+ O(g) $\to$ H2O(l) 
C) C(graphite)+ 4H(g) $\to$CH4(g) 
D) 6C(graphite)+ 6H2O(s) $\to$ C6H12O6(s) 
E) 2C(graphite)+ 3H2(g)+

O2(g) $\to$ C2H5OH(l)

Question 2

Standard heats (enthalpies)of formation of compounds,$\Delta$H°f ,may be positive or negative.

Accepted Answer

A) True 
 B)False

Question 3

Calcium hydroxide,which reacts with carbon dioxide to form calcium carbonate,was used by the ancient Romans as mortar in stone structures.The reaction for this process is

What is the enthalpy change if 3.8 mol of calcium carbonate is formed?

Accepted Answer

A) -18 kJ 
B) -69 kJ 
C) -73 kJ 
D) -260 kJ 
E) None of these choices is correct.

Question 4

Cold packs,whose temperatures are lowered when ammonium nitrate dissolves in water,are carried by athletic trainers when transporting ice is not possible.Which of the following is true of this reaction?

Accepted Answer

A) ($\Delta$H  0,process is exothermic) 
C) ($\Delta$H  0,process is endothermic) 
E) ($\Delta$H = 0,since cold packs are sealed)

Question 5

An ideal gas (the system)is contained in a flexible balloon at a pressure of 1 atm and is initially at a temperature of 20.°C.The surrounding air is at the same pressure,but its temperature is 25°C.When the system has equilibrated with its surroundings,both systems and surroundings are at 25°C and 1 atm.In changing from the initial to the final state,which one of the following relationships regarding the system is correct?

Accepted Answer

A) ($\Delta$E  0 
E) q > 0

Question 6

When Karl Kaveman adds chilled grog to his new granite mug,he removes 10.9 kJ of energy from the mug.If it has a mass of 625 g and was at 25°C,what is its new temperature? Specific heat capacity of granite = 0.79 J/(g·K)

Accepted Answer

A) 3°C 
B) 14°C 
C) 22°C 
D) 47°C 
E) None of these choices is correct.

Question 7

Which one of the following equations represents the formation reaction of CH3OH(l)?

Accepted Answer

A) C(g)+ 2H2(g)+

O2(g) $\to$CH3OH(l) 
B) C(g)+ 4H(g)+ O(g) $\to$ CH3OH(l) 
C) C(graphite)+ 4H(g)+ O(g) $\to$ CH3OH(l) 
D) C(diamond)+ 4H(g)+ O(g) $\to$ CH3OH(l) 
E) C(graphite)+ 2H2(g)+

O2(g) $\to$ CH3OH(l)

Question 8

a.A gas sample absorbs 53 kJ of heat and does 18 kJ of work.Calculate the change in its internal energy.
b.A system expands against a constant pressure of 1.50 atm,from an initial volume of 1.00 L to a final volume of 10.0 L.Calculate the work (w)involved in this process,in kJ.

Accepted Answer

The answer of a.A gas sample absorbs 53 kJ of...

Question 9

Which one of the following relationships is always correct?

Accepted Answer

A) potential energy + kinetic energy = constant 
B) E = q + w 
C) ($\Delta$E = $\Delta$H - P$\Delta$V) 
D) H = E + PV 
E) ($\Delta$H = qv)

Question 10

Calculate the $\Delta$H°rxn for the decomposition of calcium carbonate to calcium oxide and carbon dioxide.
$\Delta$H°f [CaCO3(s)] = -1206.9 kJ/mol;$\Delta$H°f [CaO(s)] = -635.1 kJ/mol;$\Delta$H°f [CO2(g)] = -393.5 kJ/mol
CaCO3(s)$\to$CaO(s)+ CO2(g)

Accepted Answer

A) -2235.5 kJ 
B) -1448.5 kJ 
C) -178.3 kJ 
D) 178.3 kJ 
E) 2235.5 kJ

Question 11

Although internal energy (E)is more fundamental and conceptually easier than enthalpy (H),in most chemical applications $\Delta$H is more relevant and useful than $\Delta$E.Why?

Accepted Answer

The answer of Although internal energy (E)is more fundamental and...

Exam 6: Thermochemistry: Energy Flow and Chemical Change

Which one of the following is a correct formation reaction?

Standard heats (enthalpies)of formation of compounds, $\Delta$ H°_f ,may be positive or negative.

Calcium hydroxide,which reacts with carbon dioxide to form calcium carbonate,was used by the ancient Romans as mortar in stone structures.The reaction for this process is What is the enthalpy change if 3.8 mol of calcium carbonate is formed?

Cold packs,whose temperatures are lowered when ammonium nitrate dissolves in water,are carried by athletic trainers when transporting ice is not possible.Which of the following is true of this reaction?

When Karl Kaveman adds chilled grog to his new granite mug,he removes 10.9 kJ of energy from the mug.If it has a mass of 625 g and was at 25°C,what is its new temperature? Specific heat capacity of granite = 0.79 J/(g·K)

Which one of the following equations represents the formation reaction of CH₃OH(l) ?

a.A gas sample absorbs 53 kJ of heat and does 18 kJ of work.Calculate the change in its internal energy. b.A system expands against a constant pressure of 1.50 atm,from an initial volume of 1.00 L to a final volume of 10.0 L.Calculate the work (w)involved in this process,in kJ.

Which one of the following relationships is always correct?

Calculate the $\Delta$ H°_rxn for the decomposition of calcium carbonate to calcium oxide and carbon dioxide. $\Delta$ H°_f [CaCO₃(s) ] = -1206.9 kJ/mol; $\Delta$ H°_f [CaO(s) ] = -635.1 kJ/mol; $\Delta$ H°_f [CO₂(g) ] = -393.5 kJ/mol CaCO₃(s) $\to$ CaO(s) + CO₂(g)

Although internal energy (E)is more fundamental and conceptually easier than enthalpy (H),in most chemical applications $\Delta$ H is more relevant and useful than $\Delta$ E.Why?

Exam 6: Thermochemistry: Energy Flow and Chemical Change

Which one of the following is a correct formation reaction?

Standard heats (enthalpies)of formation of compounds, Δ\DeltaΔ H°f ,may be positive or negative.

Calcium hydroxide,which reacts with carbon dioxide to form calcium carbonate,was used by the ancient Romans as mortar in stone structures.The reaction for this process is What is the enthalpy change if 3.8 mol of calcium carbonate is formed?

Cold packs,whose temperatures are lowered when ammonium nitrate dissolves in water,are carried by athletic trainers when transporting ice is not possible.Which of the following is true of this reaction?

When Karl Kaveman adds chilled grog to his new granite mug,he removes 10.9 kJ of energy from the mug.If it has a mass of 625 g and was at 25°C,what is its new temperature? Specific heat capacity of granite = 0.79 J/(g·K)

Which one of the following equations represents the formation reaction of CH3OH(l) ?

a.A gas sample absorbs 53 kJ of heat and does 18 kJ of work.Calculate the change in its internal energy. b.A system expands against a constant pressure of 1.50 atm,from an initial volume of 1.00 L to a final volume of 10.0 L.Calculate the work (w)involved in this process,in kJ.

Which one of the following relationships is always correct?

Calculate the Δ\DeltaΔ H°rxn for the decomposition of calcium carbonate to calcium oxide and carbon dioxide. Δ\DeltaΔ H°f [CaCO3(s) ] = -1206.9 kJ/mol; Δ\DeltaΔ H°f [CaO(s) ] = -635.1 kJ/mol; Δ\DeltaΔ H°f [CO2(g) ] = -393.5 kJ/mol CaCO3(s) →\to→ CaO(s) + CO2(g)

Although internal energy (E)is more fundamental and conceptually easier than enthalpy (H),in most chemical applications Δ\DeltaΔ H is more relevant and useful than Δ\DeltaΔ E.Why?

Standard heats (enthalpies)of formation of compounds, $\Delta$ H°_f ,may be positive or negative.

Which one of the following equations represents the formation reaction of CH₃OH(l) ?

Calculate the $\Delta$ H°_rxn for the decomposition of calcium carbonate to calcium oxide and carbon dioxide. $\Delta$ H°_f [CaCO₃(s) ] = -1206.9 kJ/mol; $\Delta$ H°_f [CaO(s) ] = -635.1 kJ/mol; $\Delta$ H°_f [CO₂(g) ] = -393.5 kJ/mol CaCO₃(s) $\to$ CaO(s) + CO₂(g)

Although internal energy (E)is more fundamental and conceptually easier than enthalpy (H),in most chemical applications $\Delta$ H is more relevant and useful than $\Delta$ E.Why?