How is mm of Hg per degree Celsius converted to kPa per degree Celsius? I also need the equation for computing the value of A (slope) in mm of Hg per degree Celsius.

  • 2
    $\begingroup$ Is this a homework question? $\endgroup$ – Neo Sep 22 '14 at 17:51
  • $\begingroup$ This is not a homework question. $\endgroup$ – user903 Sep 23 '14 at 5:01

You can convert mm Hg to kPa with the conversion factor $0.133322368\ \mathrm{kPa\ mmHg^{-1}}$.

Saturation vapor pressure as a function of temperature is

$$ e_s(T) = e_{s0}\exp\left[\left(\dfrac{L_v(T)}{R_v}\right)\left(\dfrac{1}{T_0} -\dfrac{1}{T} \right)\right], $$

where $L_v(T)$ is the specific enthalpy of vaporization, $R_v$ is the specific gas constant for water vapor, $T_0$ is reference temperature (273.15 K) and $e_{s0}$ is the saturation vapor pressure at $T_0$ (611 Pa).

You can find the slope of this curve by taking the derivative $\dfrac{d e_s}{dT}$.

Note that the units of $e_s$ and $T$ are Pa and K respectively in the equation above.

  • $\begingroup$ he could also do it through wolfram alpha if its only a few conversions =) $\endgroup$ – Neo Sep 22 '14 at 20:39
  • $\begingroup$ Well, Thank you for replying. I know the relation between kPa and mmHg. But I need to express the slope in mmHg/degree celsius instead of kPa/degree celsius. I need an equation for finding that. $\endgroup$ – user903 Sep 23 '14 at 5:05

finally i could find out that both units are not compatible to convert. Little bit speculated about the fact.
The equation for finding the slope in mmHg/°C = 4098*(4.584*exp(17.27*T/237.3+T))/(T+237.3)^2.


Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.