Barium Sulfate Conductivity

Chemicals and Solutions

• 100 mL of 0.05M Ba(OH)
• 300 mL of 0.05M HSO

Materials

• 600 mL beaker or large glass crystallizing dish
• Stir plate and stir bar large
• 250 mL buret
• ringstand
• electrodes with lamp

Procedure

1. Place beaker on stirplate and add magnetic stirrer
2. Clamp buret and electrodes with lamp above the beaker
3. Add 100 mL of Ba(OH) into beaker (the lamp will light up)
4. Fill buret with HSO and titrate the base. (At equivalence point the lamp goes out). A white ppt. forms.
5. Add excess of acid and the lamp will light up again.

Hint: The endpoint is quite large if a large light bulb is used (20 mL endpoint). Once the large light bulb goes off, it can be switched for a small light bulb. The small light bulb gives a better endpoint, but it is also easy to go past the endpoint.

Discussion

Barium sulfate is quite insoluble. It can even be swallowed because very little of it will dissolve in the solution of the body. Since barium sulfate is opaque to X-rays, it is used to outline the stomach and intestine for X-ray photographs.

$$\ce{ Ba(OH)2_{(aq)} + H2SO4_{(aq)} -> BaSO4_{(s)} + 2H2O_{(l)} }$$