Test electrolysis

Safety

Drive the electrodes from the electroPioreactor job, never by setting LED channel D by hand: only the job clamps electrolysis power to 10%.

1. Record the distance from the top of the Vial Cap to the bottom of each electrode.
2. Connect the electrodes to LED channel DOne of the HAT's four LED outputs, A to D. The electroPioreactor job drives the electrodes from channel D, clamped to 10% power., catch upwards.
3. Start electroPioreactor from Activities on the Manage screen. Set a long spargeBubbling gas through the culture. Here, CO₂ from the cylinder flows down the anode on a timer set in the electroPioreactor job. interval until CO₂ is set up.
4. Raise electrolysisSplitting water with an electric current: hydrogen at the cathode, oxygen at the anode. It supplies the hydrogen the HOB grow on. power in the job’s Settings panel until bubbles form.
5. Check roughly twice as many bubbles form on the cathodeThe negative electrode: a stainless steel rod. Hydrogen forms on it, so it shows about twice the bubbles of the anode. It must never be wired as the anode. as on the anodeThe positive electrode: a titanium tube coated with mixed metal oxide (IrO₂-Ta₂O₅). Oxygen forms on it, and CO₂ flows down its bore into the vial..
6. Measure the voltage across the electrodes with a multimeter, and record it.
7. If you can break into a lead, measure and record the current too.
8. Insert the vial into the Pioreactor once all vials show even electrolysis.

Notes

• If the unit misbehaves before electrolysis starts (fan starting and stopping, no response), run a self testPioreactor's built-in hardware check, run from the unit's Manage screen. It confirms each part of the unit responds. from its Manage screen. Power-cycle it if that hangs.

Parts

• 1×Vial cap and electrode holderearlier step
• 1×Pioreactor 40 ml glass vialearlier step
• 1×Pioreactor 40 ml v1.5earlier step

Tools

• 1×Vernier calliperstool
• 1×Multimetertool

Check your work

1. With electroPioreactor running, where do the bubbles form?

   • On both, about twice as many on the anode
   • On both, about twice as many on the cathode
   • On both, but only a few, and slowly
   • On neither: no bubbles at all
   Show the answer

   Answer: On both, about twice as many on the cathode

   • If you see On both, about twice as many on the anode: The leads are probably reversed. Stop the job and check red is on the anodeThe positive electrode: a titanium tube coated with mixed metal oxide (IrO₂-Ta₂O₅). Oxygen forms on it, and CO₂ flows down its bore into the vial., black on the cathodeThe negative electrode: a stainless steel rod. Hydrogen forms on it, so it shows about twice the bubbles of the anode. It must never be wired as the anode..
   • If you see On both, but only a few, and slowly: Raise electrolysisSplitting water with an electric current: hydrogen at the cathode, oxygen at the anode. It supplies the hydrogen the HOB grow on. power in the job's Settings panel, not by setting LED channel DOne of the HAT's four LED outputs, A to D. The electroPioreactor job drives the electrodes from channel D, clamped to 10% power. by hand: the job clamps power to 10% to protect the electrodes.
   • If you see On neither: no bubbles at all: Check the electrodes are on LED channel D (catch upwards), the vial holds nutrient solution or bicarbonate of equal ionic strength, and the job was started from Activities.

≈ 0.02 g CO₂e per view