How was it found that if we go $\rm 273°C$ below $0$, we would reach absolute zero. What experiment gave this result.

Charles' law states that :

Volume is directly proportional to the absolute temperature.

Was the Kelvin perhaps created as scale in which temperature and pressure of a gas are proportional?

I tried to find absolute zero in this manner with experimental data from this video.

This is my work:

$v_1$ $= \rm 112\ mL$

$t_1$ $= \rm 23°C$

$v_2$ $= \rm 138 \ mL$

$t_2$ $= \rm 100°C$

Let's define $x$ as the quantity to add to °C measurement's to satisfy Charles' law. In other words $\rm -x°C$ would be absolute zero.

\begin{equation} \frac{v_1}{v_2} = \frac{x + t_1}{x + t_2} \\ \frac{112}{138} = \frac{x + 23}{x + 100} \\ 26x = 112×100 - 138×23 \\ x = 308.69 \end{equation} I also tried other values but I am not getting the desired answer. Is there a flaw in my reasoning or does this have nothing to do with the Kelvin scale at all? If so, then how was the Kelvin scale formulated.


1 Answer 1


You reasoning and method is totally correct. Your final answer is almost correct. The problem is that you are looking at high temperatures and trying to find a number which is far away. This means that a little rounding in your numbers will have a huge impact on your answer. For example, if you try these numbers,

v1 = 111.1mL,
t1 = 23.9°C,
v2 = 138.9mL,
t2 = 99.1°C,

You will end up with 276.629 which is much closer to absolute zero.

  • $\begingroup$ This also explains why I got more and more and more inaccurate answers when using larger volumes. Thank you so much. $\endgroup$
    – febot
    Dec 9, 2020 at 10:43

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