# Sign of enthalpy for exothermic and endothermic reactions

In Cambridge Chemistry Coursebook [1, p. 94] it’s written that

A rise in temperature is given a positive sign. So the value of $$\Delta H$$ is negative for an exothermic reaction. A fall in temperature is given a negative sign. So the value of $$\Delta H$$ is positive for an endothermic reaction.

Why is the sign of enthalpy for exothermic reaction negative? Doesn’t exothermic reaction rise the temperature of surrounding?

Why is the sign of enthalpy for endothermic reaction positive? Doesn’t endothermic reaction take in energy and cool down the surrounding?

### Reference

1. Ryan, L.; Norris, R. Cambridge International AS and A Level Chemistry Coursebook, 2nd ed.; Cambridge International Examinations; Cambridge University Press: Cambridge, 2014. ISBN 978-1-107-63845-7.
• Is the rising or falling of the T that is not required here. This is often see at introductory level in spire of being unnecessary. See answer Nov 24 '18 at 15:44