Question: for an exothermic reaction qsurr is negative?
Answer: If a reaction is monitored with a thermometer and the temperature measured falls, did heat flow into the surroundings (qsurr is positive) or out of surroundings (qsurr is negative)? The heat energy lost by an exothermic reaction is characterized as a negative change of enthalpy of the reaction (ΔH°rxn ).