Question

What type of measuring device relies on Zeroth’s Law and how does it do this?

The temperature outside is 0 degrees Fahrenheit. What is the temperature in Kelvin?

An isolated system absorbs a heat transfer of 45J and performs 20 J of work. What is the internal energy of the system?

An isolated system contains some amount of internal energy. If 5 J of heat are transferred into the system, but the internal energy remains the same, how much work must be done by the system?

How much work is done by a jet engine that exerts 245 N of force over a distance of 1 km?

A gas maintains a constant pressure of 45 N/m² while being heated. The resulting change in volume is 0.78 m³. What is the work done by the gas?

The same gas in problem 6 had an internal energy of 85 J and a final volume of 2 m³. What is the enthalpy (H) of the gas?

The combustion process inside a jet engine creates 450 J of heat and does 110 J of work spinning a turbine shaft. What is the change in specific enthalpy of the gas?

Through an irreversible process, object A transfers 96 J of heat to object B. The resulting temperature of the system is 456 K. What is the entropy of the system?

For an ideal gas, if the pressure remains the same but the volume is doubled, what would you expect to happen to the temperature? Why?   **Hint: use the equation of state to help justify your answer.

Answer 1

1.

The Zeroth law of thermodynamics states that, if the first body is in thermal equilibrium with the second body and the second body is in thermal equilibrium with the third body, the first body is thermal equilibrium with the third body.

For example, assume two separate cups of boiling water. If we place a thermometer in the first cup, it gets warmed up until the temperature reaches 100C, we can thermometer is in thermal equilibrium with the first cup. Now we remove it from the first cup and insert it into the second, again it warmed up until the temperature touches 100C, the thermometer is in thermal equilibrium with the second cup, so we can say that first cup is in thermal equilibrium with the second cup.

2.

Scale to convert °F to K is

T (K) = 255.37 K

3.

Given: dQ = 45J and dW= 20J

According to the first law of thermodynamics,

dQ = dU + do

45 = dU + 20

dU = 25J

4.

For isolated system dU = 0

So dQ = dW

Ans is 5J

5.

Work is defined as the product of force into displacement.

W = F x d

W = 245 N x 1000 m

W = 245000 J

6.

The work in thermodynamics is also defined as the

dw = P. dV

dw = (45)(0.78) = 35.1 J

7.

Enthalpy is given by

dH = dU + PV

dH = 85 + (45)(2)

dH = 175 J