1# Experiment 9 - Effect of temperature and pressure on equilibrium 2 3To determine the effect of the temperature and pressure of an equilirium environment on the direction of the equilibrium reaction. Temperature is tested by adding methyl violet indicator to a solution of phosphoric acid which shows the concentration of ionised H+ and H2PO4- ions. Pressure (inversely proportional to volume) is tested with dinitrogen tetroxide and the colour change is observed.