Determination of the Specific Surface Area of an Insoluble Substance

Lab Exercise - Determination of the Specific Surface Area of an Insoluble Substance

Developed By

Center for Radiochemistry and Nuclear Materials
Department of Chemistry
Loughborough University

Learning Goals

Here the learning goals and purpose of the exercise should be presented in a reasonable way.

Explanation and Exercise Guide


Ion exchange on insoluble crystal surfaces (read)

Experimental Procedure

  1. Carefully weigh out 0.1 g of lead sulphate into each of 2 plastic scintillation vials
  2. Add 2 cm3 of 35S-labelled lead sulphate solution into each
  3. Place caps on vials and shake vigorously for 15 min
  4. Filter using a Buchner funnel and filter paper
  5. Pipette 0.5 cm3 of each filtrate onto 2 aluminium planchettes
  6. Carefully transfer the planchettes using a tray lined with absorbent tissue to the wooden block beneath the infrared lamp in the fume hood
  7. Dry under the IR lamp taking care not to leave them too long in case of fire
  8. Transfer the dried planchettes to the Geiger counter on a tray
  9. Count both on shelf 2 of the Geiger counter – count for 1 min, repeat this 3 times and average the counts obtained
  10. Pipette 0.5 cm3 of original 35S-labelled lead sulphate solution (without the addition of lead sulphate powder) onto 3rd planchette , dry and count as above
  11. Calculate the surface area, which should give a value of 104 – 105 cm2 g-1

Questions for the Students

Here there should be relevant questions regarding the theory of the exercise which should be possible to answer after the exercises have been performed. The questions should be molded into the report that the students write after the exercises in such a way that it feels natural.


How to do calculations or other important aspects for the theory that is not directly related to exercise.

Safety Aspects

  • A lab coat, gloves and safety glasses must be worn. 35S is a soft beta emitter which means that it is not readily detected. When checking the bench, hands, lab coat, etc for contamination it is necessary to use a sensitive instrument.
  • DO NOT dispose of any liquid or solid waste down sinks or in waste bins. Place in the red waste buckets provided.
  • Lead sulphate is toxic by ingestion, inhalation and skin contact. When weighing out the powder, great care must be taken to avoid creating air-borne dust.


Scintillation vials x 2
Buchner funnel
IR lamp
Tray for transfer
Lead castle Geiger counter
Scaler timer
Clamp stand + pressure tubing
1 mL pippet

0.2 g lead sulphate
Filter paper
Al planchette x 3
1 mL tips

4.5 mL 35S saturated lead sulphate (@ 0.37 kBq per mL)

Preparation for the lab Supervisor

The preparation that the lab Supervisor needs to do to ready the lab.

Feedback from Users and Supervisors

Here there should be a link to a open page where people who have used the exercise can leave feedback. How the exercises worked and troubles in performing it.