What Q10 means
The temperature coefficient Q10 tells you by what factor a rate increases when the temperature rises by 10 °C. It is widely used in biology, physiology, ecology and food science to describe how metabolism, enzyme activity, respiration or spoilage depend on temperature.
Q10 = (R2 ÷ R1) ^ (10 ÷ (T2 − T1))
R1 and R2 are the rates measured at temperatures T1 and T2, in the same units. The temperatures do not need to be exactly 10 °C apart: the exponent scales the ratio to a 10 °C step.
Example
An enzyme reaction runs at 10 units at 20 °C and 25 units at 30 °C:
Q10 = (25 ÷ 10) ^ (10 ÷ 10) = 2.5
The rate at 37 °C can then be predicted: R = R1 × Q10^((T − T1) ÷ 10) = 10 × 2.5^1.7 ≈ 47.5 units.
Typical values
| Process | Usual Q10 |
|---|---|
| Physical diffusion | about 1 to 1.5 |
| Enzyme reactions, metabolism | about 2 to 3 |
| Soil respiration | about 1.5 to 3 |
| Protein denaturation | can exceed 10 |
A Q10 near 1 means temperature barely matters; a high Q10 means the process is very sensitive to temperature.
Link with the Arrhenius equation
Q10 is a simplified form of the Arrhenius equation. Over a narrow range, they are linked by:
Ea = R × ln(Q10) × T1 × T2 ÷ 10
with temperatures in kelvin and R = 8.314 J/(mol·K). The calculator gives the equivalent activation energy from your two measurements: about 68 kJ/mol in the example. Because Arrhenius uses 1/T, Q10 itself drifts slightly with temperature, so a Q10 measured between 0 and 10 °C is not exactly the same as one measured between 30 and 40 °C.
Practical uses
- Physiology: a cold-blooded animal’s metabolic rate roughly doubles with each 10 °C rise.
- Food storage: the classic rule that spoilage roughly doubles for every 10 °C rise explains why refrigeration extends shelf life.
- Ecology: carbon release from soils as the climate warms.
Limits
Q10 only describes the range where it was measured. Above an optimum, enzymes denature and rates fall sharply, so predictions far outside the measured temperatures can be badly wrong.