# Ea is the term for activation energy, what is the mean of a in this term?

Our doctor said it is not stand for activation. it stands for something else, any help will be appreciated.

• Comments are not for extended discussion; this conversation has been moved to chat. – jonsca Jan 28 at 22:59

The subscript $$\mathrm a$$ in $$E_\mathrm a$$ may refer to Arrhenius.
The IUPAC gold book states that:

activation energy (Arrhenius activation energy)
An empirical parameter characterizing the exponential temperature dependence of the rate coefficient, $$k$$, $$E_\mathrm a = RT^2 \frac{\mathrm d(\ln k)}{\mathrm dt}$$, where $$R$$ is the gas constant and $$T$$ the thermodynamic temperature.

• You haven't read any of the comments to the question, have you? :) – andselisk Jan 28 at 18:22

any one interested, the answer of our doctor is a stands for apparent or approximation value of activation energy. thanks for everyone