At what Kelvin temperature does water freeze?
a. -273 K
b. 0 K
c. 273 K
The correct answer and explanation is:
The correct answer is c. 273 K.
Water freezes at 0°C (Celsius), and the Kelvin scale is an absolute temperature scale. It is used in scientific contexts because it starts at absolute zero, the point where all molecular motion theoretically ceases.
The relationship between the Celsius (°C) scale and the Kelvin (K) scale is given by the equation:
K=°C+273.15K = °C + 273.15
So, to convert 0°C (the freezing point of water in Celsius) to Kelvin:
0°C+273.15=273.15K0°C + 273.15 = 273.15 K
In most practical contexts, the value is rounded to 273 K.
Water freezes at 273.15 K, but in most situations, the rounded value 273 K is used.
The Kelvin scale starts at absolute zero, which is the theoretical temperature at which all matter would have minimal thermal energy. At this point, molecules would have no kinetic energy, and thus, no movement would occur. The freezing point of water in Kelvin is significant because the Kelvin scale is used extensively in scientific disciplines like physics and chemistry. By using this scale, scientists ensure that calculations involving temperature are grounded in absolute measurements. This is important because the Kelvin scale avoids the negative values present in Celsius and Fahrenheit, making it useful for thermodynamic calculations, particularly when dealing with gas laws, entropy, and other fundamental physical concepts.