How many seconds long is this chemistry class if it lasts 40.0 minutes?

Around 2,400 seconds would be in a 40 minute class

Explanation:

4×6=24+2 zeros on the end

answer: enthalpy

explanation:

for a exothermic reaction, the energy is released i.e. the energy of the products is lower than the energy of the reactants.

= enthaply

= energy of products

= energy of reactants

as , thus comes out to be negative. negative value of enthalpy shows that the reaction is exothermic.