Resumo em inglês This paper describes an experiment to teach the principles of gas chromatography exploring the boiling points and polarities to explain the elution order of a series of alcohols, benzene and n-propanone, as well as to teach the response factor concept and the internal standard addition method. Retention times and response factors are used for qualitative identification and quantitative analysis of a hypothetical contamination source in a simulated water sample. The intern (mais) al standard n-propanol is further used for quantification of benzene and n-butanol in the water sample. This experiment has been taught in the instrumental analysis course offered to chemistry and oceanography students.
Determinação da entalpia de vaporização de líquidos pelo método do isoteniscópio de Smith e Menzies/ Determination of the enthalpy of vaporization of liquid compounds by the Smith Menzies (isoteniscope) method
Resumo em inglês This article proposes an experimental procedure to determine the enthalpy (and entropy) of vaporization of organic liquid compounds, by the Smith-Menzies (isoteniscope) method. The values of vapor pressure at different temperatures were obtained and ΔvH (and ΔvS) were graphically determined, using the Clausius-Clapeyron equation. The results for diethyl-ether, propanone, ethanol and n-hexane are in very good agreement with those from literature. A historical and (mais) thermodynamic discussion on equations that correlates vapor pressures and temperature precedes the experimental proposition.