Preview

Molecular Diffusion

Powerful Essays
Open Document
Open Document
2566 Words
Grammar
Grammar
Plagiarism
Plagiarism
Writing
Writing
Score
Score
Molecular Diffusion
ABSTRACT
A molecular diffusion experiment was conducted with the goal of determining the diffusion coefficient of acetone into air. For this experiment, acetone was placed in a capillary tube and was allowed to diffuse into non-diffusing air that was passed over the test tube at the temperature of 50oC.Thetemperature is kept constant and air stream is passed over the top of the tube to ensure that the partial pressure of the vapor is transferred from the surface of the liquid to be air stream bymolecular diffusion. The initial reading and every 2 minutes subsequent reading of the liquidacetone level are determined, and the experiment is conducted for 10 minutes. The experiment is repeated by changing temperature to 45oC and50oC. A graph of t/L-Loagainst L-Lois plotted and best fit of straight line and slope of the graph are obtained. The diffusivity of acetone at twodifferent temperatures is determined through calculation. The diffusivity of acetone at temperature of 40oC, 45oC and 50oCare 8.415 x 10-5 m2/s , 3.6006x 10-8 m2/s and 2.3980 x 10-8 m2/s respectively. Throughoutthe experiment, the diffusivity of acetone is determined to be higher at higher temperature.This fits the theory where temperature affects the diffusion rate. Several recommendation should be taken during operating this experiment to minimize the errors.

INTRODUCTION
Mass transport in a gas or liquid generally involves the flow of fluid (e.g. convection currents) although atoms also diffuse. Solids on the other hand, can support shear stresses and hence do not flow except by diffusion involving the jumping of atoms on a fixed network of sites. Diffusion can be divided into two types which are diffusion in a uniform concentration gradient and diffusion in a non-uniform concentration. Uniform concentration obeys Fick’s first law where the constant of proportionality is called the diffusion coefficient in m2s−1. Fick’s first law applies to steady state flux in a uniform concentration gradient. The diffusion

You May Also Find These Documents Helpful

  • Good Essays

    2. Purpose: The purpose of this lab is to help give visual understanding of diffusion which is a solution of high concentration spontaneously (no energy required) moving to an area of low concentration. Also taking a look at osmosis, which is the movement of chemicals across the cell membrane. Osmosis requires some type of energy to be put in for this to happen. After these experiments we should have a better idea and visualization of how chemicals transfer across the cell membrane.…

    • 657 Words
    • 3 Pages
    Good Essays
  • Better Essays

    Oxford Tutorial

    • 1838 Words
    • 8 Pages

    Diffusion is the movement of molecules from an area of higher concentration to an area of lower concentration. Diffusion is a type of passive transport, because molecules are always in random motion, and as a result, will naturally balance a difference in concentration, and move from an area of higher concentration to an area of relative lower concentration.…

    • 1838 Words
    • 8 Pages
    Better Essays
  • Satisfactory Essays

    Cell Life

    • 510 Words
    • 3 Pages

    As temperatures increase, molecular movement increases. As the movement increases, so will the diffusion rate as the molecules spread faster and faster. The opposite would be true of colder temperatures.…

    • 510 Words
    • 3 Pages
    Satisfactory Essays
  • Good Essays

    - In this experiment three zip-loc bags were filled with a solution of starch. Each bag was placed in different beakers filled with IKI indicator and placed at different temperatures. When Iodine reacts with starch, it turns purple. The rate that a solution diffuses along a grain or membrane Is related to the concentration, the type of membrane and the temperature. Because the concentration of the solutions and type of membrane is the same, the only factor to determine the rate of diffusion in this experiment is the temperature. When molecules are placed in a hot temperature they become excited; And the higher the temperature the higher the rate of diffusion.That is why in this experiment, the zip-loc placed in the hot water bath achieved the fastest rate of diffusion when compared to the solutions placed in the refrigerator and in ambient room air.…

    • 1354 Words
    • 6 Pages
    Good Essays
  • Satisfactory Essays

    Lab 6 Diffusion

    • 325 Words
    • 2 Pages

    3. The rate of diffusion does change after time. The longer the dye sits the less it spreads in the liquid.…

    • 325 Words
    • 2 Pages
    Satisfactory Essays
  • Good Essays

    Diffusion and Glucose

    • 1471 Words
    • 6 Pages

    Why do you think the urea was not able to diffuse through the 20 MWCO membrane? How well did the results compare with your prediction?…

    • 1471 Words
    • 6 Pages
    Good Essays
  • Powerful Essays

    In Table 1, as the amount of glucose increased, the diffusion rate increased as well. Also, as the protein carriers increased so did the rate. With this evidence, it can be proven that the amount of carrier proteins and the concentration of a solute will affect the rate of diffusion. The diffusion goes down the concentration gradient, so it makes sense that as the levels of solute increase so does the rate. For example, when the amount of glucose was 8mM and the number of glucose carriers was 700, the rate was the fastest because the concentration of glucose and protein carriers was greater than any other trial. (Table 1) These trials give a thorough explanation of how facilitated diffusion works and how molecules move down a concentration gradient. It was also found that NaCl did not have an affect on the rate of diffusion of glucose. It was be determined by running a trial with all other variables the same but instead of running deionized water, running NaCl. When comparing the results, the rate of diffusion of glucose remained the same with, or without the…

    • 686 Words
    • 3 Pages
    Powerful Essays
  • Good Essays

    Diffusion is the movement of molecules or ions down a concentration gradient i.e. from an area of high concentration to an area of low concentration. For a diffusion system to be efficient, it should have a large surface area so that high amount of substances can be exchanged at a time. It should also have a thin membrane and a continuous supply of substances, as a thin membrane means that the diffusion pathway would be short, and the continuous supply helps maintain a concentration gradient, which is essential for diffusion to take place. There are two main types of diffusion; simple and facilitated. Simple diffusion is when a small, non-polar molecule such as CO2 and Oxygen passes through the phospholipid bilayer. A carrier protein is not needed for this type of diffusion to take place. Facilitated diffusion, however, requires carrier proteins transport molecules across the membrane, as the molecules are polar or are too large to pass through the lipid bilayer. Examples of these molecules are sodium and potassium ions, and glucose.…

    • 1009 Words
    • 5 Pages
    Good Essays
  • Powerful Essays

    Biology Study Guide

    • 1398 Words
    • 6 Pages

    _____________________________________________________________ _____________________________________________________________ 3. Describe how each of the following affect the rate of diffusion. a. b. 4. Molecular size:____________________________________________…

    • 1398 Words
    • 6 Pages
    Powerful Essays
  • Good Essays

    Ap Biology Lab 1 Report

    • 480 Words
    • 2 Pages

    Diffusion occurs when a system is not at equilibrium. Several factors affect how fast a molecule will diffuse. The first of these is the kinetic energy of the molecule, which is most frequently measured as the temperature of the system. The size of the molecule also affects how rapidly it will diffuse. Diffusion can occur through a cell membrane. The membrane allows small molecules like water (H2O), oxygen (O2), carbon dioxide (CO2), and others to pass through easily. It is said to be permeable to these molecules.…

    • 480 Words
    • 2 Pages
    Good Essays
  • Powerful Essays

    In this experiment we observed carmine powder to better understand the concept of Brownian motion and the role of molecular movement in diffusion. The particles continuously moved in a completely random fashion, and the smaller particles moved with more speed than the larger particles.…

    • 2788 Words
    • 12 Pages
    Powerful Essays
  • Good Essays

    BSC2085L Anatomy Quiz 1

    • 550 Words
    • 3 Pages

    Diffusion is the movement of particles from a region of high concentration to a region of low concentration.…

    • 550 Words
    • 3 Pages
    Good Essays
  • Satisfactory Essays

    I predict that the higher the concentration of acid the faster the reaction will be.…

    • 328 Words
    • 2 Pages
    Satisfactory Essays
  • Good Essays

    Diffusion is simply the net movement of atoms or molecules from a region of higher concentration to a region of lower concentration. The force behind the movement is heat or kinetic energy (also called Brownian motion). Diffusion occurs when you spill water on the carpet floor and it spreads out, or when you open a bottle of perfume and it leaves the bottle and spreads throughout the air in the room.…

    • 1013 Words
    • 4 Pages
    Good Essays
  • Good Essays

    Molecules are constantly moving. They move in straight lines unless they are deflected by other molecules or obstacles in their environment. Diffusion is the process by which the collisions between molecules cause them to continually spread apart from each other. Their movement can be described as movement from an area of greater concentration to an area of lower concentration. Diffusion continues until the molecules are equally distributed, that is their concentration is equal throughout the area that contains them. At this point, the molecules continue to move and collide, but their concentration remains the same throughout the area of containment. When certain molecules encounter artificial membranes with pores, they may be able to pass through. If the molecules are small enough to pass through the pores, their movements eventually will cause the concentration of these molecules inside and outside of the membrane to equalize. Living cells are surrounded by a membrane that acts as a selective barrier between the contents of the cell and its environment. The membrane is selectively permeable; it allows some molecules and other particles to enter and exit while blocking others. Even small molecules that could ordinarily pass through may be blocked. There permeability of the membrane can change depending on changes in the internal or external environment of the cell.…

    • 937 Words
    • 4 Pages
    Good Essays