| In The Science Behind Hydrogen Hybrid Cars - The | | | | that electrolyte will compete with the hydroxide ions |
| Equations of Electrolysis we looked at the details of | | | | for its electron. If you choose an electrolyte anion |
| the scientific equations of electrolysis, now let's | | | | that has a less standard electrode potential, than the |
| discuss the electrolytes we've talked about in your | | | | hydroxide, it will oxidize instead of the hydroxide and |
| hydrogen automobile. | | | | you won't get any oxygen. Likewise, a cation that |
| If the processes we discussed in The Equations of | | | | has a greater standard electrode potential than the |
| Electrolysis were to happen in pure water then the | | | | hydrogen ion it will reduce instead, and you won't get |
| H+ cations (positively charged ion that's attracted to | | | | any hydrogen. |
| a negative electrode in an electrolyte) will gather at | | | | Since you're looking for cations that have a lower |
| the anode and the OH- anions (negatively charged ion | | | | electrode potential than H+ try using one of the |
| that's attracted to a positive electrode in an | | | | following electrolyte cations for best results in your |
| electrolyte) will go to the cathode. You can verify | | | | hydrogen automobile: |
| that by using a pH tester in the water of your | | | | Li+, Rb+, K+, Cs+, Ba2+, Sr2+, Ca2+, Na+, and |
| hydrogen automobile. You'll find the water closest to | | | | Mg2+ (Lithium and Sodium are often used since they |
| the anode (positive electrode) should be acidic while | | | | make inexpensive and dissolvable salts) |
| the water by the cathode (negative electrode) is | | | | If you use an acid for the electrolyte in your |
| basic (alkaline). Charged ions resist the flow of | | | | hydrogen automobile, then the cation is H+ and |
| electricity until they've diffused away, which happens | | | | there's no competition for it from breaking down the |
| slowly, so they effectively begin to block the path. | | | | water. Sulfate (SO42-) is the most commonly used |
| That's why pure water isn't a very good electric | | | | since it rarely ever oxidizes. The standard potential of |
| conductor for your hydrogen automobile and why | | | | Sulfate to oxidize into the peroxodisulfate ion is |
| the electrolysis will happen much more slowly in it. | | | | −0.22 volts. |
| If you add an electrolyte to your hydrogen | | | | Stronger acids like Sulfuric Acid (H2SO4) or stronger |
| automobile that dissolves well in water then the | | | | bases like Sodium Hydroxide (NaOH) and Potassium |
| water's conductivity increases substantially. The | | | | Hydroxide (KOH) are also commonly used |
| electrolyte itself disassociates into its own cations | | | | electrolytes. Do not use NaCl in you hydrogen |
| and anions. The electrolyte anions will rush to the | | | | automobile because the anode will create deadly |
| anode to neutralize the positively charged H+ built up | | | | chlorine gas. |
| there. In the same way, the electrolyte cations will | | | | It is also possible to use polymer electrolyte that is |
| go to the cathode and neutralize the negatively | | | | solid, like NAFION. When applying NAFION, a special |
| charged OH− built up there. This will allow a | | | | catalyst needs to be on each side of the membrane |
| continual flow of electricity. | | | | to split the water molecules efficiently with as little as |
| You must be careful what electrolyte you choose in | | | | 1.8 Volts. |
| you hydrogen automobile. One of the anions from | | | | |