Gas Relationships

Learn the models, terms, and applications of gas relationships.

Lesson 3 of 32 parts Practice Flashcards

1/2

Gas Pressure and Simple Gas Relationships

Objective: Interpret particle collisions and one-variable models.

Gas pressure arises from momentum transfer as particles collide with container walls; in SI it is measured in pascals (Pa = N/m²). In an ideal-gas approximation with fixed amount of gas, pressure, volume, and absolute temperature obey PV = nRT. At fixed temperature and amount, pressure varies inversely with volume; at fixed volume and amount, pressure is proportional to kelvin temperature. Compressing an ideal sample from 4 L to 2 L at constant T doubles pressure. Real gases deviate at conditions where particle size or interactions matter. Use kelvin for proportional temperature calculations rather than treating Celsius zero as absence of thermal energy.

Worked examples

Try itA fixed ideal gas at constant T goes from 4 L to 2 L. How does pressure change?Show answer

1. Identify the relevant concept in this section. 2. P ∝ 1/V at fixed T and amount. 3. Answer: It doubles

Swipe sideways to move between sections

Gas Pressure and Simple Gas Relationships

Objective: Interpret particle collisions and one-variable models.

Worked examples

Try itA fixed ideal gas at constant T goes from 4 L to 2 L. How does pressure change?Show answer

1. Identify the relevant concept in this section. 2. P ∝ 1/V at fixed T and amount. 3. Answer: It doubles

Applications and Worked Problems

Objective: Apply gas relationships to calculations, evidence, and specified situations.

For a fixed amount of an approximately ideal gas, pressure, volume, and absolute temperature are linked. Boyle’s relation assumes fixed temperature; Charles’s relation assumes fixed pressure; P/T is constant at fixed volume. The ideal-gas equation PV=nRT also accounts for amount. Use kelvin for temperature and units matching the selected gas constant. Real gases depart from ideal behavior especially at high pressure or low temperature; pressure here is absolute, not gauge pressure.

Formulas

$P1V1=P2V2 at fixed n,T$
$V1/T1=V2/T2 at fixed n,P$
$PV=nRT$

Worked examples

Try itA fixed gas sample at constant temperature starts at 100 kPa and 2 L. Find volume at 200 kPa.Show answer

1. Boyle model: P1V1=P2V2. 2. V2=100×2/200=1 L.

Try itA fixed gas sample at constant pressure is 2 L at 300 K. Find volume at 600 K.Show answer

1. Charles model uses absolute temperature: V1/T1=V2/T2. 2. Doubling temp doubles V: 4 L.

You finished the reading!

Lock it in with a few practice questions. This is the last lesson in the chapter.

Practice

Previous lessonPhase Changes

Last lesson