Absolute zero

Definition

Absolute zero is the theoretical lowest temperature possible, where all molecular motion ceases. It is equal to 0 Kelvin or -273.15 degrees Celsius.

5 Must Know Facts For Your Next Test

1. Absolute zero is 0 Kelvin, equivalent to -273.15 degrees Celsius or -459.67 degrees Fahrenheit.
2. At absolute zero, the entropy of a perfect crystal reaches its minimum value according to the Third Law of Thermodynamics.
3. It is impossible to reach absolute zero, but scientists can get very close using advanced cooling techniques.
4. Absolute zero represents a point where particles have minimal vibrational motion and kinetic energy approaches zero.
5. The concept of absolute zero helps define the Kelvin scale, which is used extensively in scientific measurement.

Review Questions

• What is the temperature of absolute zero in Kelvin and Celsius?
• Why can't we reach absolute zero in practice?
• How does absolute zero relate to particle motion and kinetic energy?

Related terms

Kelvin Scale: A temperature scale that starts at absolute zero and measures thermal energy objectively.

Third Law of Thermodynamics: A law stating that as temperature approaches absolute zero, the entropy of a system approaches a constant minimum.

Entropy:

A measure of disorder or randomness in a system; at absolute zero, the entropy reaches its minimal value for a perfect crystal.