AP Thermochem Quiz Review

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Which letters show PE constant and KE increasing?

• B and D
• A and B
• A, C, and E
• D and E

The heat of combustion of pentane, C₅H₁₂ is -3509 kJ/mol_rxn. Write the balanced thermochemical equation for the combustion of pentane.

• C₅H₁₂ + 8 O₂ → 5 CO₂ + 6 H₂O + 3509 kJ
• C₅H₁₂ + 8 O₂ → 5 CO₂ + 6 H₂O - 3509 kJ
• C₅H₁₂ + 5 O₂ → 5 CO₂ + 6 H₂O + 3509 kJ
• C₅H₁₂ + 5 O₂ → 5 CO₂ + 6 H₂O - 3509 kJ

Calculate the heat transferred when 4.4 g of water cools from 87.2°C to 50.0°C.  (C = 4.18 J/g°C) 

• 680 J
• 1600 J
• -1600 J
• -680 J

Given the following information, what is the approximate ΔH_f for SO₃?
2 S(s) + 3 O₂ → 2SO₃ + 792 kJ

• -800 kJ/mol_rxn
• 800 kJ/mol_rxn
• -400 kJ/mol_rxn
• 400 kJ/mol_rxn

Given the following reaction, use the table provided to estimate the bond energy of the N-H bond.
N₂ + 3 H₂ → 2 NH₃, ΔH = -90 kJ/mol 

• 390 kJ/mol
• 780 kJ/mol
• 250 kJ/mol
• 1170 kJ/mol

What is the enthalpy change for the following reaction? 
C(s, graphite) + 1⁄2O₂(g) → CO(g)
Use the information below:
C(s, graphite) + O₂(g) → CO₂(g)      ΔH = -394 kJmol^–1
CO(g) + 1⁄2O₂(g) → CO₂(g)    ΔH = -283 kJmol^–1  

• -677 kJmol^–1 
• +111 kJmol^–1 
• -111 kJmol^–1 
• +677 kJmol^–1 

If 500 J of heat is absorbed by a sample of metal with a mass of 0.40 kg and a specific heat of 0.472 J/g°C, what is the increase in temperature of the metal? 

• 2600 °C
• 26 °C
• 2.6 °C
• 0.59 °C

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Which letters show KE constant and PE increasing?

• A, C, and E
• B and D
• A and B
• D and E

A sample of iron receives 50.J of heat energy that raises the temperature of the iron 25.0°C. If iron has a specific heat of .10 J/g°C, what is the mass of the iron sample? (show your work)

• 25g
• 30g
• 20g
• 50g

The standard enthalpy changes of formation of iron(II) oxide, FeO(s), and aluminium oxide, Al₂O₃(s), are 270 kJ mol^–1 and –1700 kJ mol^–1 respectively.
What is the enthalpy change under standard conditions for the following reaction?
3FeO(s) + 2Al(s) → 3Fe(s) + Al₂O₃(s)  

• +890 kJ/mol 
• –890 kJ/mol
• –1970 kJ/mol 
• –2510 kJ/mol