Question

Which temperature scale has its zero point set at absolute zero, the lowest possible temperature?

Hint:

Think of the SI base unit of temperature, the one used in gas law equations, with no negative values.

Answer 1

Step 1: Absolute zero is the theoretical lowest possible temperature, at which the particles of a substance have the minimum possible thermal motion. It equals -273.15 degrees Celsius.

Step 2: The Celsius and Fahrenheit scales set their zero points at arbitrary reference points, the freezing point of water for Celsius, and a mixture of ice, salt and water for Fahrenheit. Neither starts at absolute zero.

Step 3: The Kelvin scale, proposed by Lord Kelvin, was designed so that its zero, called 0 K, coincides exactly with absolute zero. There are no negative temperatures on this scale.

Step 4: The size of one kelvin is kept equal to the size of one degree Celsius, so converting is simple: \( T(\text{K}) = T(^{\circ}\text{C}) + 273.15 \).

Answer: The Kelvin scale is the temperature scale whose zero is set at absolute zero.