The laboratory production of sulphuric acid involves the catalysed oxidation of sulphur in oxygen, followed by the separation of the resulting sulphur trioxide (SO3) from sulphur dioxide (SO2) as shown below: sulphur trioxide is collected as solid crystals in trap A, and sulphur dioxide is collected as a liquid in trap B, which consists of a sealable ampoule.
(a) The vapour pressure of SO2 is 0.0167 x 105 Pa at its triple point temperature of 197.7 K, and its enthalpy of vaporisation is reported as 26000 J mol-1. Upon collection, the SO2 is to be stored in the ampoule B sealed by taps t, which has a maximum pressure tolerance of 8 atmospheres.
Use the Clausius-Clapeyron equation to estimate the boiling temperature of SO2 at atmospheric pressure (1 atm = 1.013 x 105 Pa), and estimate whether the ampoule can safely be stored at a room temperature of 22 °C.
(b) In order to ensure that the SO2 is retained, the experimenter considers increasing the pressure inside the apparatus to 2 atm, but then wonders if the increased pressure might encourage the SO3 in trap A to melt. Comment on this.