Laws of Thermal Dynamics

If an ideal gas is compressed isothermally, which of

the following statements is true?

• Energy is transferred to the gas by heat.

• No work is done on the gas.

• The temperature of the gas increases.

• The internal energy of the gas remains constant.

• None of those statements is true

When an ideal gas undergoes an adiabatic expansion, which of the following statements is true?

• The

  temperature of the gas doesn’t change

• No work is done by the gas.

• No energy is delivered to the gas by heat

• The internal energy of the gas doesn’t change.

• The pressure increases

Tags

NGSS.HS-PS3-2

By visual inspection, order the PV diagrams shown in Figure 12.4 from the most negative work done on the system to the most positive work done on the system.

• a, b, c, d

• a, c, b, d

• d, b, c, a

• d, a, c, b

When an ideal gas expands at constant pressure, the change in the internal energy must be positive.

• True

• False

Tags

NGSS.HS-PS3-1

What is the equation for the first law of thermodynamics?

A gas is heated by supplying it with 250 kJ of

energy; at the same time, it is compressed

so that 500 kJ of work is done on the gas.

Calculate the change in the internal energy of

the gas.

• 250 kJ

• 750 kJ

• -250 kJ

• 500 kJ

Tags

NGSS.HS-PS3-1

A heat engine

• converts heat input to an equivalent amount of work

• converts work to an equivalent amount of heat

• takes heat in, does work, and loses energy heat

• uses positive work done on the system to transfer heat from a low temperature reservoir to a high temperature reservoir

• uses positive work done on the system to transfer heat from a high temperature reservoir to a low temperature reservoir

Tags

NGSS.HS-PS3-4

A Carnot cycle

• is bounded by two isotherms and two adiabats on a p-V graph

• consists of two isothermal and two constant volume processes

• is any four sided process on a p-V graph

• only exists for an ideal gas

• has an efficiency equal to the enclosed area on a p-V diagram

Tags

NGSS.HS-PS3-4

A Carnot engine operates between 200°C and 20°C. Its maximum possible efficiency is

• 90%

• 100%

• 38%

• 24%

• 72%

Tags

NGSS.HS-PS3-4

Which of the following statements best describes the Second Law of Thermodynamics?

• The internal energy of the universe is constant.

• Energy can be neither created nor destroyed.

• When an isolated system undergoes a spontaneous change, the entropy of the system will increase.

• At absolute zero, the entropy of a perfect crystal is considered to be zero.