Homework Answers

Hess’s law applies the rule that enthalpy is an ________.

a. extensive process.

b. intensive property.

c. intensive process

d. extensive property.

The heat capacity of a substance is determined ______________.

a. by a constant specific heat values regardless of physical states.

c. through careful measure of specific heat values.

c. through calorimetry.

d. by increasing the temperature by 1°C.

Hess’s law states that the __________________.

a. enthalpy of a sum of a series of reactions is equal to the sum of the enthalpies of those two reactions.

b. enthalpy of a sum of two reactions is equal to the difference of the enthalpies of those two reactions.

c. enthalpy of a sum of a series of reactions is equal to the sum of the heat capacities of those two reactions.

d. enthalpy of a sum of a series of reactions is unequal to the sum of the enthalpies of those two reactions.

Heat is a form energy transfer between objects as an effect of their difference in _________.

a. volume

b. energy

c. pressure

d. temperature

Calorimetry involves the measurement of the ___________________.

a. quantity of heat exchanged between a system and the surroundings.

b. quantity of work exchanged between a systems.

c. quantity of work exchanged between a system and the surroundings.

d. quantity of heat exchanged between the systems.

Explosion of a firecracker triggered by a spark is _________.

a. endothermic

b. exothermic

c. partly exothermic

d. both endothermic and exothermic

Enthalpy of reaction is positive when _______________.

a. chemical reaction is endothermic.

b. chemical reaction is both endothermic and exothermic.

c. chemical combustion does not happen.

d. the amount of heat transferred and absorbed are unequal.

Law of Conservation of Energy states that, ______________.

a. Energy can neither be created nor destroyed.

b. The change in energy of a system is equal to the heat absorbed and released.

c. The energy of the system and the of the surroindings are unrelated.

d. Energy can neither be created nor transferred.

The most stable conformation of butane is anti conformation and it's least stable conformation is eclipsed conformation. Why?

When work is accomplished on the system, it _________

a. gains work and energy is denoted as positive.

b. gains energy and work is denoted as positive.

c. gains work and energy is denoted as zero.

d. gains energy and work is denoted as negative.

A calorimeter is an____________________.

a. apparatus that has water or any liquid with unknown heat capacity.

b. insulated coffee cup that that transfers an immense amount of heat.

c. excellent insulator that works without a thermometer.

d. insulated apparatus that contains water or any liquid of known heat capacity.

The study of energy and heat flow that goes with a chemical reaction and physical transformation.

a. Thermodynamics

b. Enthalpy

c. Conservation of Energy

d. Thermochemistry

At 34.1^oC, the vapor pressure of water is 40.1 torr. What is the vapor pressure at 85.5^oC? The Δ

H_vap of water is 40.7 kJ/mol.

Acetone is essential as an industrial solvent and a starting reactant in the manufacturing of countless products, from films to synthetic fibers. At 20.2^oC, the vapor pressure of acetone is 24.50 kPa. If its Δ H_vap is 30.99 kJ/mol, what is the temperature (in ^oC) when the vapor pressure is 10.00 kPa?

The symbol, q-, means ___________.

a. Work is done on the surroundings.

b. Heat flows from the system to the surroundings.

c. Work is done on both the system and the surroundings.

d. Heat flows from the surroundings to the system.

The amount of energy needed to increase the temperature of a material by 1°C.

a. coffee cup calorimeter

b. heat constant

c. specific heat transfer

d. heat capacity

When heat flows from the system to its surroundings, heat is ________.

a. positive

b. negative

c. equal

d. neutral

It shows the value and direction of heat involved in a reaction.

a. thermochemical reaction

b. enthalpy of reaction

c. thermochemical equation

d. enthalpy