Vapor Pressure Lab

. Introduction

Vapor pressure is the tendency of the liquid to evaporate and the amount of gas at equilibrium, while vapor is when molecules move from a liquid phase to a gaseous state. Vapor is basically what liquid produces after it starts evaporating. Liquids evaporate because some portions of their molecules have sufficient energy to flee from the liquid phase and become vapor. Some liquids even evaporate faster than other liquids. This is because some of these liquids can be more volatile than others which can lead to a faster rate of evaporation and because it also depends on the intermolecular forces strength. The intermolecular forces between the molecules are a major factor that effects and influences the vapor pressure of a substance.

Part A included some volatile compounds that were studied in this experiment. The volatile compounds included methanol, ethanol, 1-propanol, and 1-butanol. However, my group used ethanol, while the other groups used the other different compounds. These compounds were similar because they had the same type of intermolecular forces, and they were different because of their vapor pressures. The measured vapor pressures of the volatile compounds are below in the data sheet; however, the vapor pressure for my groups volatile compound which was ethanol was 48.9 mmHg. The relationship between the vapor pressures and molecular weights of this volatile compound is that the higher the molecular weight, the lower the vapor pressure would be and/or vice-versa. This is because when the molecular weight increases, the dispersion forces also increase. When this happens, the molecules in the liquid state are held very securely and the change from a liquid into a gas is prevented and so, the vapor pressure

I can infer that the relationship between vapor pressure and the molecular weight is inversely proportional, because when molecular weight increases, the vapor pressure decrease. The relationship of vapor pressure and structure is that if it is a straight-chained compound, it will have more surface area which means that it will result in a low vapor pressure, which makes the intermolecular forces stronger. The relationship between the vapor pressure and temperature has a direct relationship. This has a direct relationship because when the temperature increases, so do the vapor pressure. The compound is more dangerous and volatile when the vapor pressure at a certain temperature is higher. After observing my data, methanol was the most volatile in the first and third portion of the lab, and 2-butanone was the most volatile in the second portion of the lab. There are many different practical applications of vapor pressure and this experiment. A perfect example of when the vapor pressure is very important is when one needs to check any substances’ boiling