What is enthalpy a measure of?
the heat content of a system.
the kinetic energy of a system.
the number of moles of reactant in a system.
the disorder of a system.

Awhite powder is added to a solution. the images show observations made before the powder is added, just after the powder has been added, and a little while later. (the liquid in the small beaker is phenol red solution.) what evidence shows that a chemical change has taken place?