Unit Test — Unit test Answers

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Carbon reacts with oxygen to produce carbon dioxide (CO2 (g), Hf = –393.5 kJ/mol) according to the equation below.What is the enthalpy change of the reaction? Use .

–393.5 kJ

–196.8 kJ

196.8 kJ

393.5 kJ

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Propane (C3 H8 (g), Hf = –103.8 kJ/mol) reacts with oxygen to produce carbon dioxide (CO2 , Hf = –393.5 kJ/mol ) and water (H2 O, Hf = –241.82 kJ/mol) according to the equation below.What is the enthalpy of combustion (per mole) of C3 H8 (g)? Use .

–2,044.0 kJ/mol

–531.5 kJ/mol

531.5 kJ/mol

2,044.0 kJ/mol

The combustion of glucose, C6 H12 O6 (s), produces carbon dioxide, CO2 (g), and water, H2 O(g), according to the equation below.The enthalpy of the reaction is –2,840 kJ. What is the heat of combustion, per mole, of glucose?

–2,840 kJ/mol

–473.3 kJ/mol

473.3 kJ/mol

2,840 kJ/mol

Which substance has Hf defined as 0 kJ/mol?

H2O (s)

Ne (l)

F2 (g)

CO2 (g)

Which statement describes mechanical energy?

the energy that is stored in chemical bonds

the energy that is associated with temperature

the sum of the kinetic energy and the potential energy of an object

the type of energy that is associated with electromagnetic radiation

Digby wants to determine how many calories are in his bag of chips. Which calorimeter should he use?

coffee cup calorimeter

bomb calorimeter

He could use both types of calorimeters.

He cannot use either.

A copper rod that has a mass of 200.0 g has an initial temperature of 20.0°C and is heated to 40.0°C. If 1,540 J of heat are needed to heat the rod, what is the specific heat of copper?Use .

0.0130 J/(gi°C)

0.0649 J/(gi°C)

0.193 J/(gi°C)

0.385 J/(gi°C)

A book is falling from the top shelf of a bookcase. Which statement correctly describes the change in the energy of the book?

The potential energy and kinetic energy remain the same.

The potential energy decreases as kinetic energy increases.

The kinetic energy decreases as potential energy increases.

The kinetic energy remains at zero, but potential energy increases.

Consider the following equation.Fe2O3(s) + 3H2(g) 2Fe(s) + 3H2O(g)H = 98.8 kJ, and S = 141.5 J/K. Is this reaction spontaneous or nonspontaneous at high and low temperatures?

spontaneous at high temperatures, nonspontaneous at low temperatures

nonspontaneous at high and low temperatures

spontaneous at low temperatures, nonspontaneous at high temperatures

spontaneous at high and low temperatures

Which statement best explains the change that occurs when gas particles move more slowly?

The temperature increases because the average kinetic energy decreases.

The temperature increases because the average kinetic energy increases.

The temperature decreases because the average kinetic energy decreases.

The temperature decreases because the average kinetic energy increases.

Reactant P contains 50 J of energy, and reactant Q contains 35.3 J of energy. The reactants combine to form product PQ, which contains 104 J of energy. What is the energy transformation?

Energy is absorbed because the product has more energy than the reactants have.

Energy is absorbed because the product has less energy than the reactants have.

Energy is lost because the product has more energy than the reactants have.

Energy is lost because the product has less energy than the reactants have.

A sample of octane (C8H18) that has a mass of 0.750 g is burned in a bomb calorimeter. As a result, the temperature of the calorimeter increases from 21.0°C to 41.0°C. The specific heat of the calorimeter is 1.50 J/(g • °C), and its mass is 1.00 kg. How much heat is released during the combustion of this sample?Use .

22.5 kJ

30.0 kJ

31.5 kJ

61.5 kJ

When ammonium chloride is dissolved in water, the beaker gets cold. Which type of reaction does this describe?

exothermic

endothermic

both exothermic and endothermic

neither exothermic nor endothermic

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