Question

In terms of Charles’ law explain why –273°C is the lowest possible temperature. 

Answer 1

Charles observed that the volume of certain amount of a gas changes by  V_O / 273.15 for each

degree rise or fall in temperature.V_O being the volume at 0°C.The volume at any temperature t°C  

is given by

V_t  = V_O(1 + t°C/ 273.15)

Now ,if the temperature is lowered,it becomes clear that at t = -273.15°C

V_t  = V_O(1+ (-273.15/273.15))

= V_O  = (1-1) = 0

And below t = -273.15°C, Vt  becomes negative, which is not possible

Therefore the physically significant lowest temperature is -273.15° C

Answer 2

Charles’ law states that at constant pressure, the volume of a fixed mass of gas is directly proportional to its absolute temperature. 

It was found that for all gases (at any given pressure), the plots of volume vs. temperature (in °C) is a straight line. If this line is extended to zero volume, then it intersects the temperature-axis at – 273°C. In other words, the volume of any gas at – 273°C is zero. This is because all gases get liquefied before reaching a temperature of – 273°C. Hence, it can be concluded that – 273°C is the lowest possible temperature.