Does the energy go from the surrounding to the chemicals or from the chemicals to the surround in an exothermic reaction?

The most efficient way to establish the best possible economizer position is to measure

Describe the difference between a. a hypothesis and a theory and b. an observation and an experiment.

)benzene and toluene form nearly ideal solutions. consider an equimolar solution of benzene and toluene. at 20 °c the vapour pressures of pure benzene and toluene are 9.9 kpa and 2.9 kpa, respectively. the solution is boiled by reducing the external pressure below the vapour pressure. calculate (i) the pressure when boiling begins, (ii) the composition of each component in the vapour, and (iii) the vapour pressure when only a few drops of liquid remain. assume that the rate of vaporization is low enough for the temperature to remain constant at 20 °c.