Question 6 5. You wish to measure the changes in pressures of gases during the course of a reaction using a closed-end mercury manometer. Suppose 720 mmHg N204 is allowed to react to form NO2 according to the reaction, N2O4(g) â 2 NO2(g). The total pressure you measure, as the reaction proceeds, is the sum of the pressures of N204 and NO2 present. When the total pressure is 1150 mmHg, what is the pressure of N204? (mmHg)