Particle Motion
How do particles move in a solid?
They vibrate in a fixed position
Temperature is related to what property of particle motion?
Average kinetic energy
What is heat?
Energy transferred because of a temperature difference.
Convert 32°F to °C.
Calculation: (32 − 32) × 5/9 = 0°C.
How does particle motion in a gas differ from particle motion in a solid?
Gas particles move freely and randomly through much more space, while particles in a solid mainly vibrate around fixed positions.
Which has greater average particle kinetic energy: an object at 20°C or one at 80°C?
80 degree object
In what direction does heat spontaneously transfer between objects at different temperatures?
From the higher-temperature object to the lower-temperature object.
Convert 68°F to °C.
Calculation: (68 − 32) × 5/9 = 36 × 5/9 = 20°C.
What is Brownian motion?
The irregular/random motion of visible or suspended particles caused by collisions with much smaller surrounding particles.
What is absolute zero?
The lowest possible temperature
What is thermal equilibrium?
The condition in which objects in thermal contact have reached the same temperature and there is no net heat transfer between them.
Convert 104°F to °C.
Calculation: (104 − 32) × 5/9 = 72 × 5/9 = 40°C.
Why does Brownian motion provide evidence that tiny particles are moving even when we cannot directly see those tiny particles?
The observed irregular motion can be explained by collisions from constantly moving surrounding particles.
Two cups contain the same substance. One is warmer. What can you conclude about the average kinetic energy of its particles?
The warmer sample has greater average kinetic energy.
A hot cup of water sits in a cooler room. What eventually happens?
Energy transfers from the hotter water to the cooler surroundings until thermal equilibrium is approached.
Convert 38°C to °F.
Calculation: (38 × 9/5) + 32 = 68.4 + 32 = 100.4°F.
A sealed sample of gas is warmed. What happens to the average kinetic energy and motion of its particles?
Average kinetic energy increases and the particles move faster on average.
Explain why knowing an object's temperature alone does NOT necessarily tell you its total thermal energy.
Total thermal energy depends on factors beyond temperature, including the amount and type/state of matter; temperature describes average particle kinetic energy rather than total energy.
A student says, “Temperature, thermal energy, and heat are all basically the same thing.” Correct the statement.
Temperature relates to average particle kinetic energy; thermal energy refers to internal energy associated with the particles of a system; heat is energy transferred because of a temperature difference.
A student converts 95°F by multiplying by 5/9 FIRST and subtracting 32 afterward. Explain the mistake and find the correct temperature.
The formula requires subtracting 32 first: (95 − 32) × 5/9 = 63 × 5/9 = 35°C.