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Temperature Coefficient (*Q*_{10}) Calculator

The **temperature coefficient (***Q*_{10}) represents the factor by which the rate (*R*) of a reaction increases for every 10-degree rise in the temperature (*T*). The rate (*R*) may represent any measure of the progress of a process. For example, the rate may be the velocity of action potential propagation along a nerve fiber (e.g., m/s), or it may be the rate at which the products of a chemical reaction are produced (e.g., mmol/s), or it may be the current (electrical equivalent of ionic flux) conducted through an ion channel, pump, or transporter (e.g., pA, nA, μA, etc.), or it may be the rate at which the heart contracts per minute (i.e., beats per minute, bpm). In a typical experiment, the rate of the physiological process under investigation is measured at two different temperatures, *T*_{1} and *T*_{2} (where *T*_{2} > *T*_{1}), thus yielding the rate measurements *R*_{1} (measured at *T*_{1}) and *R*_{2} (measured at *T*_{2}), respectively. The *Q*_{10} equation (see below) is then used to estimate the *Q*_{10} for the process. The temperature unit must be either the Celsius or the Kelvin, and may not be any other unit, such as the Fahrenheit. Note that *T*_{1} and *T*_{2} do not need to be exactly 10 degrees apart in order to use this equation. Keep in mind that the same unit must be used for the two temperatures (*T*_{1} and *T*_{2}) at which the rate measurements are obtained. Moreover, the rate measurements (*R*_{1} and *R*_{2}) must have the same unit. *Q*_{10} values are useful because they may be used to infer mechanistic insight about the physiological process under investigation (see below).

Temperature coefficient (*Q*_{10}) equation

is the*Q*_{10}*factor*by which the reaction rate increases when the temperature is raised by ten degrees.*Q*_{10}is a unitless quantity.is the measured reaction rate at temperature*R*_{1}*T*_{1}(where*T*_{1}<*T*_{2}). Note that*R*_{1}and*R*_{2}must have the same unit.is the measured reaction rate at temperature*R*_{2}*T*_{2}(where*T*_{2}>*T*_{1}). Note that*R*_{1}and*R*_{2}must have the same unit.is the temperature at which the reaction rate*T*_{1}*R*_{1}is measured (where*T*_{1}<*T*_{2}). The temperature unit must be either the Celsius or the Kelvin, and may not be any other unit, such as the Fahrenheit. Note that*T*_{1}and*T*_{2}must have the same unit.*T*_{1}and*T*_{2}do not need to be exactly 10 degrees apart.is the temperature at which the reaction rate*T*_{2}*R*_{2}is measured (where*T*_{2}>*T*_{1}). The temperature unit must be either the Celsius or the Kelvin, and may not be any other unit, such as the Fahrenheit. Note that*T*_{1}and*T*_{2}must have the same unit.*T*_{1}and*T*_{2}do not need to be exactly 10 degrees apart.

Each calculator cell shown below corresponds to a term in the formula presented above. Enter appropriate values in all cells except the one you wish to calculate. *Therefore, at least four cells must have values, and no more than one cell may be blank*. The value of the blank cell will be calculated based on the other values entered. After a calculation is performed, the calculated cell will be highlighted and subsequent calculations will calculate the value of the highlighted cell (with no requirement to have a blank cell). However, a blank cell has priority over a highlighted cell.

Please note that the unit of temperature used in the above equation must be in Celsius or Kelvin (not Fahrenheit). If your temperature values are in Fahrenheit, please first convert them to corresponding values in Celsius or Kelvin.

Interpretation of *Q*_{10}

Although the *Q*_{10} is a convenient way to examine and report the temperature dependence of a process, it must be kept in mind that a thorough examination of the temperature dependence of a process requires that the rate be measured at more than two temperatures. Typically, the rate of the reaction is measured at multiple (5 or more) temperatures that reasonably represent the relevant physiological temperature range. The data collected are then plotted in an Arrhenius plot, which yields the activation energy (*E*_{a}) for the process under investigation. Similar to *Q*_{10}, *E*_{a} is also used to infer mechanistic information about the process, but *E*_{a} is thought to be a better approach.

Posted: Tuesday, December 20, 2005

Last updated: Sunday, March 2, 2014

Last updated: Sunday, March 2, 2014