Classify each of the observed changes according to whether or not they are likely to represent evidence that a chemical
reaction is occurring when performing an experiment.

May be evidence of a chemical reaction

Not evidence of a chemical reaction

Answer Bank
a solid liquifying
precipitation
change in temperature
solution colors mixing
a solution color becoming less intense due to dilution
bubbles (gas formation)
changes in color
explosion or fire

Jose and eric were given four samples in lab. the results of their analysis are shown in the table. based on the data they collected, which sample is most likely a metal?

Which of the following are sources of revenue for media companies? a. direct sales to producers b.advertising and subscriptions c. online purchase d. capital investments

)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.