The Effect of Different Molar Mass on the Diffusion on Substances
The Effect of Different Molar Mass on the Diffusion on Substances
Lunar-maius A. Gaerlan
Group 2 Sec. X – 9l
August 15, 2012
ABSTRACT
The effect of molecular weight on the rate of diffusion was assessed using agar-water gel test. The agar-water gel set up was composed of a petri dish of agar-water gel containing three wells. Drops of potassium permanganate (KMnO4), potassium dichromate (K2Cr2O7) and methylene blue(C16H18N3SCl) were simultaneously introduced to each well. Methylene blue, having the largest molecular weight, displayed the smallest diameter (11 mm) and diffused at the slowest rate (0.20 mm/min.). Next is potassium dichromate with a diameter of 24 mm and rate of diffusion of 0.30 mm/min.. The fastest is the potassium permanganate with 19 mm diameter and diffusion rate of 0.47 mm/min.. Thus, the higher the molecular weight, the slower the rate of diffusion.
INTRODUCTION
A substance in the gaseous or liquid state consists of molecules or atoms that are independent, rapid, and random in motion. These molecules frequently collide with each other and with the sides of the container. In a period of time, this movement results in a uniform distribution of the molecules throughout the system. This process is called diffusion (Everett and Everett, n.d.). Diffusion occurs naturally, with the net movement of particles flowing from an area of high concentration to an area of low concentration. Net diffusion can be restated as the movement of particles along the concentration gradient.
According to Meyertholen (n.d.), there are several factors which may affect the rate of diffusion of a substance. These factors include the size of the particle or the molecular weight of the substance, temperature or availability of energy in the system, difference in concentrations inside the system, diffusion distance, and if the system involves a membrane or barrier, surface area of the barrier, and the barrier’s permeability. The greater the concentration of a
Lunar-maius A. Gaerlan
Group 2 Sec. X – 9l
August 15, 2012
ABSTRACT
The effect of molecular weight on the rate of diffusion was assessed using agar-water gel test. The agar-water gel set up was composed of a petri dish of agar-water gel containing three wells. Drops of potassium permanganate (KMnO4), potassium dichromate (K2Cr2O7) and methylene blue(C16H18N3SCl) were simultaneously introduced to each well. Methylene blue, having the largest molecular weight, displayed the smallest diameter (11 mm) and diffused at the slowest rate (0.20 mm/min.). Next is potassium dichromate with a diameter of 24 mm and rate of diffusion of 0.30 mm/min.. The fastest is the potassium permanganate with 19 mm diameter and diffusion rate of 0.47 mm/min.. Thus, the higher the molecular weight, the slower the rate of diffusion.
INTRODUCTION
A substance in the gaseous or liquid state consists of molecules or atoms that are independent, rapid, and random in motion. These molecules frequently collide with each other and with the sides of the container. In a period of time, this movement results in a uniform distribution of the molecules throughout the system. This process is called diffusion (Everett and Everett, n.d.). Diffusion occurs naturally, with the net movement of particles flowing from an area of high concentration to an area of low concentration. Net diffusion can be restated as the movement of particles along the concentration gradient.
According to Meyertholen (n.d.), there are several factors which may affect the rate of diffusion of a substance. These factors include the size of the particle or the molecular weight of the substance, temperature or availability of energy in the system, difference in concentrations inside the system, diffusion distance, and if the system involves a membrane or barrier, surface area of the barrier, and the barrier’s permeability. The greater the concentration of a
Cited: Ben-Avraham, D. and S. Havlin. 2000. Diffusion and Reactions in Fractals and Disordered Systems. USA: Cambridge University Press. Chang, R. 1998. Chemistry. 6th ed. Boston: James M. Smith. Everett, G.W and G.W. Everett, Jr. (n.d.). Diffusion of Gases and Graham’s Law. Retrieved Aug. 14, 2011 from http://www.cerlabs.com/experiments/1087540412X.pdf Meyertholen, E. (n.d.) Diffusion. Retrieved Aug. 14, 2011 from http://www.austincc.edu/ ~emeyerth/diffuse2.htm Nave, R. 2008. Diffusion. Retrieved Aug. 14, 2011 from http://hyperphysics.phy-astr.gsu.edu/hbase/kinetic/diffus.html Weiss, G. 1994. Aspects and Applications of the Random Walk. Amsterdam, Netherlands: North-Holland.