Acetic anhydride has an enthalpy of vaporization of 45.5 kj/mol and a vapor pressure of 4.0 mmhg at 20 °c. calculate the vapor pressure at 50 °c using the clausius-clapeyron equation: (lnp2/p1) = -(δhvap/r)(1/t2-1/t1). (note: p must be in atm, t in kelvin, r = 8.3145 j/kmol) report your final answer in mmhg. osha\'s permissible exposure limit (pel) for acetic anhydride is 5 ppm in air and the immediate danger to life and health (idlh) value is 200 ppm in air. the vapor concentration in ppm immediately above a liquid can be determined by dividing the vapor pressure by 760 mmhg and then multiplying by 106: (p2/760 x 106). calculate the vapor concentration at 20 °c and 50 °c. which of these concentrations exceeds the pel and which exceeds the idlh? what should be done to reduce the probability of exposure?