For every degree Celsius increase, the reaction rate approximately doubles? (temperature rule)

• A. 10
• B. 5
• C. 20
• D. 15

Answer: (A)

Reaction rate sensitivity to temperature is described by the Q10 rule: for many biochemical reactions, the rate doubles with about a 10°C increase in temperature. This is because increasing temperature provides more kinetic energy, helping more molecules overcome the activation energy barrier, which speeds up collisions that lead to product formation. However, the doubling effect is not seen with every single degree; a 10°C step tends to give roughly a twofold increase, while smaller or larger steps give smaller or larger multipliers (for example, a 5°C rise gives about a 1.4× increase, a 20°C rise about a 4× increase, and a 15°C rise around 2.8×). Therefore, the temperature change that commonly yields a doubling of the rate is 10°C.