Electrolysis of Sodium Bicarbonate to produce Copper Carbonate

Electrolysis of Aqueous Sodium Bicarbonate Using Copper To Produce Copper Carbonate.

Experiment done by Andrew and Autumn Spangler for HomeLink Science Fair

Question: How does the amount of time spent electrolysing aqueous sodium bicarbonate (NaHCO3) at 12 volts 2 amps using copper affect the resulting colour of the product?

    Hypothesis: The longer the time spent electrolysing, the bluer the product will become. I believe this because the solution will become increasingly saturated with copper ions and those copper ions will react with the sodium bicarbonate and water to produce sodium carbonate, copper carbonate, copper hydroxide, sodium hydroxide, carbon dioxide, and hydrogen.

    Materials:

50 ml Beaker

100 ml Beaker

25 ml sodium bicarbonate

12V 2A switching power supply

Water

Copper wire, 12 gauge

Evaporating dish

Electrical or Duct tape
Small Glass Jar 
Stirrer
Acetic acid

Procedure:

1. Gather materials

2. Measure 50 ml of hot water in the 100 ml beaker

3. Measure 25 ml sodium bicarbonate into the 50 ml beaker

4. Add water to 50 ml beaker

5. Bend copper wires and attach to power supply wires with power supply still unplugged  

6. Tape power supply wires down

7. Insert wires into 50 ml beaker with the bent parts over the lip

8. Observe beaker

9. Plug in power supply

10. Observe reaction, taking note every thirty seconds for five minutes

11. Take note every 5 minutes until 30 minutes

12. Record final observation at 1 hour
13. Add 80 ml of boiling water to 100 ml beaker
14. Filter out water from from electrolyzing beaker and scrape resulting solids into 100 ml beaker
15. Stir 100 ml beaker contents
16. Re-filter mixture 
17. Scrape solids into evaporating dish
18. Wait until solids dry
19. Crush resulting material with mortar and pestle until a fine powder
20. Store resulting powder in jar. To test material, add acetic acid, if the material bubbles and becomes a green solution the material is copper carbonate.

Data:

Time	Observations
0 seconds	water is clear, undissolved sodium bicarbonate on bottom of beaker.
30 seconds	water is light clear blue
1 minute	slightly darker clear blue
1 min 30s	darker blue
2 minutes	blue chunks falling
2 min 30 s	chunks are depositing on bottom of glass
3 minutes	chunks reacting with sodium bicarbonate
3 min 30 s	darker blue
4 minutes	same
4 min 30 s	even darker blue
5 minutes	deep blue, very blue
10 minutes	really light blue, opaque, slightly green
15 minutes	aquamarine, opaque
20 minutes	same colors, but much larger buildup of copper carbonate
25 minutes	more precipitant
30 minutes	top buildup, brown/green bottom buildup, green/turquoise
1 hour	large amounts of precipitant, greenish black, buildup of copper on cap of negative terminal

Notes:

6:30 water becomes slightly cloudy - completely opaque and darkish blue

9:00 light blue, opaque

11:00 green flocculence

17:15 lighter green layer stacked on top of darker lower one

19:17 some green gathers on side

Reactions:

2H2O + 572 kJ  → H2+ + 2OH-

Cu(II) + 2OH- → Cu(OH)2

2 NaHCO3 + energy  → 2 Na2CO3 + H2O + CO2

Cu(OH)2  + Co2 → CuCO3 + H2O

2 Na2CO3 + 4 OH- → 4 NaOH + 2 Co2 + O2

Conclusion: My hypothesis was correct in that, the longer time I spent electrolysing the solution, the darker the colour the water became. At first, the water was a transparent dark blue. Eventually the water became an opaque light blue and finally a blue powdery slime. The materials copper hydroxide and copper carbonate gave a blue colour to the liquid. The carbon dioxide, hydrogen, and oxygen all bubbled out, and the sodium hydroxide was clear. 
 (c) Copyright Andrew and Autumn Spangler  2013