Absolute Zero

We have learned about thermodynamics in our previous sessions. We know that ideal gas is a theoretical gas composed of randomly moving particles that are not under the influence of interparticle interactions. Gases behave differently at different temperatures. Let us know how gases behave at absolute zero and also learn what is absolute zero.

What is Absolute Zero Temperature

Temperature is a physical quantity and is the measure of the hotness or coldness of a substance. Every matter in the universe has a temperature. Temperature is the representation of the thermal energy present in the body/object. The SI unit of temperature is Kelvin. Temperature is different from heat. Temperature is an essential measuring parameter used in each and every field. The thermometer is a device that measures the temperature. Scales to measure the temperature are the

• Celsius scale (°C)
• Fahrenheit scale (°F)
• Kelvin scale (K)

The Celsius scale was also known as the centigrade scale. Now let us know what is meant by absolute zero temperature. Absolute zero is the lowest possible temperature where heat energy is absent in a substance. Absolute zero is also known as zero kelvin temperature since it measures zero on the Kelvin scale. Minimal vibrational motion is displayed at this temperature by fundamental particles of nature.

Note: The value of the absolute zero is 459.76 degrees Fahrenheit on the Fahrenheit scale and -273.15 degrees Celsius on the Celsius scale.

The lowest temperature a thermodynamic system can withstand is 459.76 degrees Fahrenheit and -273.15 degrees Celsius. The absolute zero temperature is a theoretical value. Some of the highlights of temperature recorded are:

• In the year 1994, a record cold temperature of 700 nK (billions of kelvin) was achieved by The National Institute of Standards and Technology (NIST).
• A temperature of 0.45 nK (billions of kelvin) was recorded at the Massachusetts Institute of Technology (MIT) in the year 2003.

Kelvin is the globally recognized scale for measuring temperature. Absolute temperature scale or a thermodynamic scale is defined as a temperature scale that features absolute zero for its zero point. Let us now know the behaviour of gases in absolute zero temperature.

Behaviour of Gases at Absolute Zero

We know that as the temperature gets colder the particles of gas start to slow down. At absolute zero, the particles stop moving but will have some energy. Molecules and atoms of matter showcase minimum vibrational motion by retaining only quantum mechanical, zero-point energy-induced particle motion.

It is a common thought to imagine that particles freeze completely, and stop moving by becoming stagnant at absolute zero. This is not true. According to Heisenberg’s uncertainty principle, the measurements of sub-atomic particles cannot be pinned exactly. Therefore, a particle cannot be completely stopped to know its exact position and momentum.

For ease of understanding, heat cannot be completely removed from a system at absolute zero temperature, due to the presence of internal heat stored in the system. Hence, absolute zero does not represent the lowest possible enthalpy state. According to quantum mechanics, the lowest internal energy of solid matter is in its zero/ground state.

The concept of absolute zero came to existence while studying and analysing the behaviour of a gas at various temperatures. At lower temperatures, gases contract as temperature reduces. Ideal gas reaches zero volume when pressure is constant.

Real gas condenses to a liquid or a solid at a certain higher temperature than absolute zero. Hence, the ideal gas law is one of the methods to predict the behaviour of real gas.

Absolute Zero Formulas

The temperature scale is the fundamental part of a measuring device like a thermometer. The temperature scale starts at zero degrees. Zero degrees represents the freezing point and 100 degrees represents the boiling point.

The absolute scale that corresponds to the Fahrenheit scale is called the Rankine (R) scale. The zero points on the Celsius scale and Fahrenheit scale specify the same physical state. The following equations give the relationships between the relative and absolute temperature scales:

Kelvin to Celsius

K = °C + 273.15

°C = K – 273.15

Rankine to Fahrenheit

R = °F + 460

°F = R – 460

Watch the below video and know more about temperature.

Similar Reading: Temperature – Definition, Measurement, Temperature Units