Skip to main content
Ch 19: The First Law of Thermodynamics
Young & Freedman Calc - University Physics 14th Edition
Young & Freedman Calc14th EditionUniversity PhysicsISBN: 9780321973610Not the one you use?Change textbook
Chapter 19, Problem 10

Five moles of an ideal monatomic gas with an initial temperature of 127127°C expand and, in the process, absorb 15001500 J of heat and do 21002100 J of work. What is the final temperature of the gas?

Verified step by step guidance
1
Convert the initial temperature from Celsius to Kelvin by adding 273.15. The initial temperature in Kelvin is T1 = 127 + 273.15.
Use the first law of thermodynamics, which states that the change in internal energy (ΔU) is equal to the heat added to the system (Q) minus the work done by the system (W). So, ΔU = Q - W.
Substitute the given values into the equation: Q = 1500 J and W = 2100 J. Calculate ΔU = 1500 J - 2100 J.
For an ideal monatomic gas, the change in internal energy can also be expressed as ΔU = (3/2) * n * R * ΔT, where n is the number of moles, R is the ideal gas constant (8.314 J/(mol·K)), and ΔT is the change in temperature.
Rearrange the equation to solve for the final temperature T2: ΔT = ΔU / ((3/2) * n * R). Then, T2 = T1 + ΔT. Substitute the values to find T2.

Verified video answer for a similar problem:

This video solution was recommended by our tutors as helpful for the problem above.
Video duration:
5m
Was this helpful?

Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Ideal Gas Law

The Ideal Gas Law is a fundamental equation in thermodynamics, expressed as PV = nRT, where P is pressure, V is volume, n is the number of moles, R is the universal gas constant, and T is temperature in Kelvin. It describes the relationship between these variables for an ideal gas, allowing us to predict how a gas will behave under different conditions.
Recommended video:
Guided course
07:21
Ideal Gases and the Ideal Gas Law

First Law of Thermodynamics

The First Law of Thermodynamics, also known as the law of energy conservation, states that the change in internal energy of a system (ΔU) is equal to the heat added to the system (Q) minus the work done by the system (W). Mathematically, it is expressed as ΔU = Q - W. This principle is crucial for understanding energy transfer in thermodynamic processes.
Recommended video:
Guided course
08:04
The First Law of Thermodynamics

Monatomic Gas Specific Heat Capacity

For a monatomic ideal gas, the molar specific heat capacity at constant volume (Cv) is 3/2 R, where R is the universal gas constant. This value is derived from the degrees of freedom of monatomic gases and is used to calculate changes in internal energy and temperature when the gas undergoes processes at constant volume or when the volume changes.
Recommended video:
Guided course
06:50
Specific Heat & Temperature Changes
Related Practice
Textbook Question

A gas in a cylinder is held at a constant pressure of 1.80×1051.80\(\times\)10^5 Pa and is cooled and compressed from 1.701.70 m3 to 1.201.20 m3. The internal energy of the gas decreases by 1.40×1051.40\(\times\)10^5 J. Does it matter whether the gas is ideal? Why or why not?

2
views
Textbook Question

A gas in a cylinder expands from a volume of 0.1100.110 m3 to 0.3200.320 m3 . Heat flows into the gas just rapidly enough to keep the pressure constant at 1.65×1051.65\(\times\)10^5 Pa during the expansion. The total heat added is 1.15×1051.15\(\times\)10^5 J. Find the work done by the gas.

1
views
Textbook Question

The pVpV-diagram in Fig. E19.1319.13 shows a process abcabc involving 0.4500.450 mol of an ideal gas. How much heat had to be added during the process to increase the internal energy of the gas by 15,00015,000 J?

1
views
Textbook Question

The process abcabc shown in the pVpV-diagram in Fig. E19.1119.11 involves 0.01750.0175 mol of an ideal gas. What was the lowest temperature the gas reached in this process? Where did it occur?

3
views
Textbook Question

Figure E19.819.8 shows a pVpV-diagram for an ideal gas in which its absolute temperature at bb is one-fourth of its absolute temperature at aa. Did heat enter or leave the gas from aa to bb? How do you know?

1
views
Textbook Question

In Fig. 19.719.7a, consider the closed loop 132411 → 3 → 2 → 4 → 1. This is a cyclic process in which the initial and final states are the same. Find the total work done by the system in this cyclic process, and show that it is equal to the area enclosed by the loop.

2
views