Set up electrolysis

Safety

Fix the red cable to the platinum-plated titanium anode and the black cable to the stainless steel cathode. Never swap them. Reversed, the stainless steel cathode dissolves into the culture.

1. Seat the cap O-ring in the O-ring vial cap, and an electrode O-ring in each electrode bore.
2. Push the stainless steel 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. very gently up through 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.’s O-ring with a twisting motion, then twist it back out. This eases the O-ring for the more delicate anode.
3. Twist the cathode up through its own O-ring.
4. Unwrap the platinum-plated titanium anode without touching its platinised section, and twist it gently up through its O-ring.
5. Check both electrode O-rings are still seated.
6. Adjust both electrodes so their bases are 33 mm below the bottom of the vial cap. Measure with the vernier callipers.
7. Lay each electrode cable’s ring terminal in the ElectrodeTopStop so it will meet its electrode when the bolt is tightened: red on the anode side, black on the cathode side.
8. Push the ElectrodeTopStopThe printed block that sits on top of the MEP's O-ring vial cap. It holds both electrodes parallel and clamps each cable's ring terminal to its electrode with an M3 bolt through a captive nut. down fully onto the electrodes.
9. Tighten the red cable onto the anode with an M3 bolt through the captive M3 nut, using the 2.5 mm hex key: firmly, not hard.
10. Tighten the black cable onto the cathode the same way.
11. Check both bases are still 33 mm below the cap.

Notes

• The electrodes are 60 mm long, so 33 mm below the cap puts both well into the 14 ml working volume.
• Overtightening a bolt can crack the ElectrodeTopStop. Stop once the ring terminal is firm against the electrode.

Parts

• 1×O-ring vial capprinted
• 1×Vial cap O-ringpart
• 2×Electrode O-ringspart
• 1×Stainless steel cathode, 60 mm long, 6 mm diameterpart
• 1×Platinum-plated titanium anodepart
• 1×ElectrodeTopStopprinted
• 2×Wiring, electrode cablespart
• 2×Ring terminalspart
• 2×M3 boltspart
• 2×M3 nutspart

Tools

• 1×2.5 mm hex keytool
• 1×Vernier calliperstool

Check your work

1. Which electrode is the red cable bolted onto?

   • The stainless steel cathode
   • The platinum-plated titanium anode
   Show the answer

   Answer: The platinum-plated titanium anode

   • If you see The stainless steel cathode: Swap the cables now, before anything drives the electrodes: loosen both M3 bolts, swap the ring terminals, and tighten again, firmly, not hard. Reversed, the stainless steel dissolves into the solution.

2. Measured with the callipers, how far below the bottom of the vial cap are the electrode bases?

   • One or both less than 33 mm
   • Both 33 mm
   • One or both more than 33 mm
   Show the answer

   Answer: Both 33 mm

   • If you see One or both less than 33 mm: Loosen its M3 bolt, lower it to 33 mm with a gentle twist, and tighten again.
   • If you see One or both more than 33 mm: Loosen its M3 bolt, raise it to 33 mm with a gentle twist, and tighten again.

≈ 0.02 g CO₂e per view