Temperature mixing formula

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Revision as of 05:46, 25 September 2008 by Torsten Waldminghaus (Talk | contribs)
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This page is to help calculating the amount of one liquid you need to add to another to get a special temperature. This is often usefull if you perform a temperature shift for example with cultures of organisms that carry a temperature sensitive mutant.


Here is a form of Richmann’s calorimetric mixing formula:

 m_{1}= \frac{m_{2}\cdot T_{2}- T_{m}\cdot m_{2}}{T_{m}-T_{1}}

  • m1 is the mass of the liquid you want to add
  • m2 is the mass of the liquid that you have
  • T1 is the temperature of the liquid you want to add
  • T2 is the temperature of the liquid you have
  • Tm is the temperature that you want to have after mixing


Suppose you have a 100 ml culture at 39°C and want to shift it to 30°C with the help of 4°C cold fresh medium.

  • m2=100
  • T1=4
  • T2=39
  • Tm=30

Than the formula is:

 m_{1}= \frac{100\cdot 39- 30\cdot 100}{30-4}

That means that m1 is 34.6, so if you add 34.6 ml of 4°C cold fresh medium to your culture it will be 30°C warm.

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