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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 21b

A gas at 100°C fills volume V₀. If the pressure is held constant, what is the volume if the Kelvin temperature is doubled?

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Step 1: Understand the relationship between temperature and volume for a gas at constant pressure. This is described by Charles's Law, which states that the volume of a gas is directly proportional to its absolute temperature (Kelvin) when pressure is constant. Mathematically, Charles's Law can be expressed as: VT = V₀T₀, where V is the final volume, T is the final temperature, V₀ is the initial volume, and T₀ is the initial temperature.
Step 2: Convert the given temperature from Celsius to Kelvin. The initial temperature is 100°C, and the Kelvin temperature is calculated using the formula: T₀ = 100 + 273.15. This gives the initial temperature in Kelvin.
Step 3: Double the Kelvin temperature. If the initial Kelvin temperature is T₀, the final Kelvin temperature T is given by: T = 2T₀. This step ensures the temperature is doubled as per the problem statement.
Step 4: Use Charles's Law to find the final volume. Rearrange the formula to solve for V: V = V₀ × TT₀. Substitute the values of T and T₀ into the equation.
Step 5: Simplify the expression for V. Since T = 2T₀, the equation becomes: V = V₀ × 2. This shows that the final volume is twice the initial volume.

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Key Concepts

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

Ideal Gas Law

The Ideal Gas Law relates the pressure, volume, temperature, and number of moles of an ideal gas through the equation PV = nRT. This law is fundamental in understanding how gases behave under varying conditions of temperature and pressure, allowing us to predict changes in volume when temperature changes.
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Temperature Scales

Temperature can be measured in different scales, with Celsius and Kelvin being the most common in physics. The Kelvin scale is an absolute temperature scale where 0 K represents absolute zero, the point at which molecular motion ceases. To convert Celsius to Kelvin, one adds 273.15, making it crucial to use Kelvin when applying gas laws.
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Charles's Law

Charles's Law states that the volume of a gas is directly proportional to its absolute temperature when pressure is held constant. This means that if the temperature of a gas increases, its volume will also increase, provided the pressure does not change. This principle is essential for solving problems involving changes in gas volume with temperature variations.
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