The liquid diffusivities coefficient apparatus has been designed to enable measurement of molecular diffuivities relating to an equimolar counter-diffusion

Description

The liquid diffusivities coefficient apparatus laboratory equipment has been designed to enable measurement of molecular diffuivities relating to an equimolar counter-diffusion process and in so doing, familiarise students with the basic notions of mass transfer theory.

Armfield has developed a unique diffusion cell which overcomes the traditional problem of slow diffusion rates in liquids requiring long observation times but without sacrificing accuracy or introducing convective effects. Essentially, the cell consists of a honeycomb of accurately dimensioned capillaries positioned between two liquids of differing concentration of the solute, whose diffusion coefficient is to be determined.

In practice, a small volume of concentrated solution is placed on one side of the honeycomb, whilst the other side consists initially of a large volume of pure solvent (water). As diffusion of the solute occurs, the concentration within the larger volume increases and is monitored with a conductivity sensor and meter.

The mixture is continuously stirred with a magnetic stirrer to ensure uniform concentration within the bulk liquid.

Whilst the conductivity sensor may be readily calibrated for any required aqueous system, for introductory studies dilute solutions of sodium chloride are recommended, for which conductivity data is provided.

Requirements

Electrical supply:

Battery operated

Software requires the user to have a PC running Windows 7 or above with a USB port.

Technical Specifications

Diffuser vessel: Capacity 1l
Conductivity meter: 3 ranges 199.9μ5 to 19.99mS
Computer output: RS232

Overall dimensions

Height: 0.31m
Diameter: 0.19m

Conductivity meter

Length: 0.25m
Width: 0.20m
Height: 0.13m