Diffusion Lab Report
1.0 Introduction
1.1 Aim and Assumptions:
The aim of this experiment is to observe the rate of diffusion of diethyl ether vapour into stagnant air, and then determine the diffusivity. An error analysis of this calculation also had to be carried out.
The following assumptions made were: * Diethyl Ether is an ideal gas * Partial pressure at the top of the tube was equal to zero * Mass transfer resistance between the liquid surface at the bottom of the tube is insufficient, compared with the resistance in the tube * Mole fraction of Diethyl Ether at xA,O is the same as the liquid surface
1.2 Background Information:
Diffusion occurs throughout the human body, and without it, cells would not get the nutrients they need for survival. Diffusion is where a concentration gradient between two areas causes the transportation of molecules from high to low concentration. This process naturally occurs and is used in many different ways, like in the human body. The diffusion rate is a function of temperature and not affected by concentration. However, diffusivity (or diffusion coefficient) is proportionality constant between molar flux (due to molecular diffusion) and the gradient in the concentration of the species. For example the diffusivity of diethyl ether in air; this depends on the temperature, pressure, the properties of the substance and the container used for diffusion. This experiment incorporates evaporation rate versus diffusion rate of diethyl ether using different length apparatuses.
1.3 Theory:
Diethyl ether is an organic compound with a high flammability and low boiling point. This makes it suitable for a diffusion analysis experiment. The rate at which diethyl ether diffuses through a solid material is very slow, so this rate is assumed to be negligible. The diethyl ether contains intermolecular bonds that hold it together. In diffusion these bonds and broken using heat energy. There is flux of diethyl ether away from the liquid surface that is due
1.1 Aim and Assumptions:
The aim of this experiment is to observe the rate of diffusion of diethyl ether vapour into stagnant air, and then determine the diffusivity. An error analysis of this calculation also had to be carried out.
The following assumptions made were: * Diethyl Ether is an ideal gas * Partial pressure at the top of the tube was equal to zero * Mass transfer resistance between the liquid surface at the bottom of the tube is insufficient, compared with the resistance in the tube * Mole fraction of Diethyl Ether at xA,O is the same as the liquid surface
1.2 Background Information:
Diffusion occurs throughout the human body, and without it, cells would not get the nutrients they need for survival. Diffusion is where a concentration gradient between two areas causes the transportation of molecules from high to low concentration. This process naturally occurs and is used in many different ways, like in the human body. The diffusion rate is a function of temperature and not affected by concentration. However, diffusivity (or diffusion coefficient) is proportionality constant between molar flux (due to molecular diffusion) and the gradient in the concentration of the species. For example the diffusivity of diethyl ether in air; this depends on the temperature, pressure, the properties of the substance and the container used for diffusion. This experiment incorporates evaporation rate versus diffusion rate of diethyl ether using different length apparatuses.
1.3 Theory:
Diethyl ether is an organic compound with a high flammability and low boiling point. This makes it suitable for a diffusion analysis experiment. The rate at which diethyl ether diffuses through a solid material is very slow, so this rate is assumed to be negligible. The diethyl ether contains intermolecular bonds that hold it together. In diffusion these bonds and broken using heat energy. There is flux of diethyl ether away from the liquid surface that is due
References: 1. Taj Pharmaceuticals, Diethyl ether, Retrieved August 12, 2011, from http://www.tajapi.com/Diethyl%20ether.htm 2 3. Mass diffusivity. (2011, June 18). In Wikipedia, The Free Encyclopedia. Retrieved 00:08, August16,2011,from http://en.wikipedia.org/w/index.php?title=Mass_diffusivity&oldid=434983443 8.0 Nomenclature