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Ch 18: A Macroscopic Description of Matter
Knight Calc - Physics for Scientists and Engineers 5th Edition
Knight Calc5th EditionPhysics for Scientists and EngineersISBN: 9780137344796Not the one you use?Change textbook
Chapter 18, Problem 67a

In Problems 67,68,69,67, 68, 69, and 7070 you are given the equation(s) used to solve a problem. For each of these, you are to write a realistic problem for which this is the correct equation(s).
p2=300 cm3100 cm3×1×2 atmp_2 = \(\frac{300 \text{ cm}\)^3}{100 \(\text{ cm}\)^3} \(\times\) 1 \(\times\) 2 \(\text{ atm}\)

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1
Step 1: Recognize that the given equation resembles the application of Boyle's Law, which states that for a fixed amount of gas at constant temperature, the product of pressure and volume remains constant: \( P_1 V_1 = P_2 V_2 \).
Step 2: Identify the variables in the equation. Here, \( P_2 \) is the final pressure, \( V_1 = 300 \; \text{cm}^3 \) is the initial volume, \( V_2 = 100 \; \text{cm}^3 \) is the final volume, and \( P_1 = 2 \; \text{atm} \) is the initial pressure.
Step 3: Write a realistic problem based on the context of Boyle's Law. For example: 'A gas is initially at a pressure of 2 atm and occupies a volume of 300 cm³. If the gas is compressed to a volume of 100 cm³ while keeping the temperature constant, what is the final pressure of the gas?'
Step 4: Rearrange Boyle's Law equation to solve for \( P_2 \): \( P_2 = \frac{P_1 V_1}{V_2} \). Substitute the given values into the equation: \( P_2 = \frac{2 \; \text{atm} \times 300 \; \text{cm}^3}{100 \; \text{cm}^3} \).
Step 5: Simplify the expression to find \( P_2 \). This step involves basic arithmetic, but the final numerical result is not calculated here as per the instructions.

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Key Concepts

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

Gas Laws

Gas laws describe the behavior of gases in relation to pressure, volume, and temperature. The ideal gas law, for example, relates these variables through the equation PV=nRT. Understanding these laws is crucial for solving problems involving gas behavior, as they provide the foundational relationships that govern how gases respond to changes in their environment.
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Pressure and Volume Relationship

The relationship between pressure and volume of a gas is often described by Boyle's Law, which states that at constant temperature, the pressure of a gas is inversely proportional to its volume. This means that if the volume of a gas decreases, its pressure increases, and vice versa. This concept is essential for understanding how changes in one variable affect the other in gas-related problems.
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Units of Measurement

In physics, using consistent units of measurement is vital for accurate calculations and problem-solving. In the context of gas laws, pressure is often measured in atmospheres (atm), volume in cubic centimeters (cm³), and temperature in Kelvin (K). Understanding how to convert between different units and apply them correctly in equations is crucial for solving real-world problems involving gases.
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Related Practice
Textbook Question

An inflated bicycle inner tube is 2.2 cm in diameter and 200 cm in circumference. A small leak causes the gauge pressure to decrease from 110 psi to 80 psi on a day when the temperature is 20°C. What mass of air is lost? Assume the air is pure nitrogen.

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Textbook Question

The cylinder in FIGURE CP18.73 has a moveable piston attached to a spring. The cylinder's cross-section area is 10 cm2, it contains 0.0040 mol of gas, and the spring constant is 1500 N/m. At 20°C the spring is neither compressed nor stretched. How far is the spring compressed if the gas temperature is raised to 100°C?

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Textbook Question

Five grams of nitrogen gas at an initial pressure of 3.0 atm and at 20°C undergo an isobaric expansion until the volume has tripled. What is the gas temperature after the expansion (in °C)? The gas pressure is then decreased at constant volume until the original temperature is reached.

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Textbook Question

In Problems 67,68,69,67, 68, 69, and 7070 you are given the equation(s) used to solve a problem. For each of these, you are to write a realistic problem for which this is the correct equation(s).

(T2+273) K=200 kPa500 kPa×1×(400+273) K(T_2 + 273) \(\text{ K}\) = \(\frac{200 \text{ kPa}\)}{500 \(\text{ kPa}\)} \(\times\) 1 \(\times\) (400 + 273) \(\text{ K}\)

1536
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Textbook Question

A container of gas at 2.0 atm pressure and 127°C is compressed at constant temperature until the volume is halved. It is then further compressed at constant pressure until the volume is halved again. Show this process on a pV diagram.

2151
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Textbook Question

Five grams of nitrogen gas at an initial pressure of 3.0 atm and at 20°C undergo an isobaric expansion until the volume has tripled. What is the gas volume after the expansion?

1528
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