There is a time delay of almost two to three minutes before the reaction proceeds because of the following processes:
<span>1) </span><span> The acid starts to go yellow as the dehydration begins.</span>
<span>2) </span><span> The rate of dehydration then accelerates as the acid heats up because the reaction is exothermic/chemical (releases energy by light or heat). As the sugar molecules are stripped of water, the heat generated turns the water into steam which then expands the remaining carbon into a porous, smoking, black column.</span>
<span>3) </span>This expands out of the reaction vessel, producing a choking acrid vapor and the smell of burned sugar.
<span> At this stage, sulfuric acid is highly corrosive and will burn skin so one must avoid contact with it. </span>