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Flip to reveal answersIn the kinetic model, what causes gas pressure?
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All 12 Flashcards — Kinetic model of an ideal gas
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Question
In the kinetic model, what causes gas pressure?
Answer
Gas particles **colliding with the walls** of the container — each collision pushes on the wall.
Question
What does the (absolute) temperature of a gas measure?
Answer
The **average kinetic energy** of its particles — hotter gas means faster particles.
Question
How does average kinetic energy depend on temperature?
Answer
It is **proportional to the absolute temperature**: average KE ∝ T (T in kelvin).
Question
Formula for the average kinetic energy of a gas particle?
Answer
$\overline{E_k} = \tfrac{3}{2}k_B T$ — **given** in the data booklet (T in kelvin).
Question
What is k_B in that formula?
Answer
The **Boltzmann constant**, 1.38 × 10⁻²³ J K⁻¹ — it links energy to temperature for one particle.
Question
Why must T be in kelvin?
Answer
The relation average KE ∝ T only works from **absolute zero** (0 K); convert Celsius with **+ 273**.
Question
Two different gases at the same temperature — compare their average KE.
Answer
**Equal** — average kinetic energy depends only on the temperature, not the gas or particle mass.
Question
Why do molecules speed up when a gas is compressed quickly?
Answer
The piston **does work** on the gas, raising the particles' average kinetic energy, so they move faster.
Question
What happens to average kinetic energy at absolute zero (0 K)?
Answer
It is **zero** — the particles have the least possible motion.
Question
List two assumptions of the ideal gas model.
Answer
Particles are tiny points with negligible volume; there are **no forces between them** except during (elastic) collisions.
Question
In an ideal gas, what kind of energy do the particles have?
Answer
**Only kinetic** energy — no intermolecular potential energy (no forces between particles).
Question
At the same temperature, why do heavier particles move more slowly?
Answer
All gases have the **same average KE** at a given temperature, so heavier particles need a **lower speed** to have that energy.
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Topic 2.3 hub
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