In this experiment students investigated the chemical significance of Avogadro's hypothesis. They determined the volume of hydrogen gas evolved in a reaction between magnesium metal and hydrochloric acid, and from their results determined the mass of H 2 produced. Their experimental results were then compared to the results predicted by Avogadro's hypothesis. In this experiment, temperature probes were placed in various liquids. Evaporation occurs when the probe is removed from the liquid's container.
Evaporation is an endothermic process that results in a temperature decrease.
The magnitude of a temperature decrease is, like viscosity and boiling temperature, related to the strength of intermolecular forces of attraction. In this experiment, students studied temperature changes caused by the evaporation of several liquids and related the temperature changes to the strength of intermolecular forces of attraction. They used the results to predict, and then measure, the temperature change for several other liquids. In addition to carbon and hydrogen atoms, alcohols also contain the -OH functional group. Methanol, CH 3 OH, and ethanol, C 2 H 5 OH, are two of the alcohols that we used in this experiment.