Preparing 30 wt% KOH - NanoLabStaff/nanolab GitHub Wiki

Preparing 30 wt% KOH

[!CAUTION]

  • Should be carried out in the Chemical Area
  • When you are not wearing PPE, ensure that the KOH pellets are not in contact with water
  • The reaction between the KOH pellets and water is exothermic. The solution will therefore heat up when mixed
  • The K ions are mobile and may penetrate normal glassware. Additionally, it is damaging to several processes. You should therefore only use the assigned KOH glassware/Teflon beakers
  • A buddy is needed for this process

You need:

  • 300 g of KOH pellets
  • 1000mL volumetric flask
  • Beakers from KOH cabinet
  • Magnetic stirrer
  • Funnel
  • Plastic spatula
  • Plastic weighing cup
  • DI water
  • 1000mL plastic storage flask
  • PPE: Apron, yellow gloves, face shield

Procedure:

  1. Weigh 300 g of KOH pellets using a plastic spatula and 2 of the largest plastic weighing cups. This does not require PPE as long as you make sure the pellets are not in contact with water.
  2. Rinse the storage flask, beakers, volumetric flasks, funnels magnetic stirrer etc with DI water before you start.
  3. Add 250 mL DI water into a beaker with a magnetic stirrer.
  4. After you have started the magnetic stirrer, add approximately half of the pellets little by little (exothermic reaction!). Let it stir until the solution is clear.
  5. Transfer the solution to the volumetric flask using a funnel.
  6. Repeat points 4 and 5 with the other half of the pellets. Make sure you rinse the plastic weighing cup with DI water into the beaker before you transfer the solution.
  7. Rinse the beaker with DI water. Add this too to the volumetric flask.
  8. Rinse the funnel and magnetic stirrer (into the volumetric flask).
  9. Top off with water until the meniscus tops the mark.
  10. Turn the volumetric flask 4 times.

    The density will increase after the volumetric flask has been turned.

  11. After this, you can rinse all equipment and the gloves with DI water in the sink, dry lightly with wipes, and let it dry in the KOH cabinet.
  12. Clean a plastic bottle with DI water and ethanol and dry it properly with an N2 gun before you add your solution to the bottle. Let the solution cool a little before you tighten the lid.
  13. Label the flask with your name, activity number, contents, the date of preparation, sticker of the semester, and the GHS05 and GHS07 pictograms (corrosive and health hazards), and store it in the Base cabinet.

Congratulations. You now have a new 30 wt% KOH solution!