I don't know that there's any agreed definition of "low" or "high" activation energies. Different reactions have a wide range of activation energies. But here's a suggestion. There is a rule of thumb that says that for many "typical" reactions the rate roughly doubles for each 10 K increase in temperature. Now, can you work out the activation energy if the rate constant increases by a factor of 2 when T increases from 300 to 310 K? If your experimental 11.5 kJ/mol [note units!] is much higher than this, I would call it "high". If it is much lower, I would call it "low".