rustyfoot7

The cells that I'm studying are galvanic (voltaic). Specifically, zinc/copper galvanic cell with a sulfuric acid electrolyte. Any ideas?

I noticed that in dry voltaic cells the "cathode" has a surplus of electrons and the "anode" has a surplus of positive charge. Electrons flow from the cathode to the anode to produce an electrical current. However, in hydrogen fuel cells the "anode" has a surplus of electrons and the "cathode" has a surplus of positive charge. Electrons flow from the anode to the cathode to produce electrical current. This is opposite from a dry voltaic cell. What's the convention for determining the anode and cathode? There's a lot of conflicting info on the internet. Thanks.

In other words, why do the reactions in the cell spontaneously occur the way they do?

Here's the simple voltaic cell that I have... One copper electrode and one zinc electrode immersed in a sulfuric acid electrolyte. There is an external load between the electrodes. The sulfuric acid ionizes into hydrogen ions and sulfate ions. H2SO4 ---> 2H+ + SO42- The sulfate ions migrate to the zinc electrode and oxidizes the zinc. Zn ---> Zn2+ + 2e- The 2 extra electrons stay on the zinc electrode and build up a potential. The hydrogen ions migrate to the copper electrode, strip 2 electrons off each copper, and form hydrogen gas. 2H+ + Cu ---> H2 + Cu2+ The excess positive charge on the copper electrode builds up a potential that causes the extra electrons on the zinc electrode to flow to the copper electrode and power the load. Here's my question... Why do the hydrogen ions strip electrons from the copper electrode and not from the zinc electrode? Likewise, why do the sulfate ions oxidize the zinc on the zinc electrode and not the copper from the copper electrode? I have a feeling this has something to do with standard electrode potential but I'm not exactly sure how it fits in. Any insight would be appreciated.

Thanks for the post! I didn't think of it in terms of inertia. Angular acceleration of the tires would decrease with increasing inertia. (Torque = Inertia x angular acceleration) However, for highway driving, where very little acceleration is needed, larger tires should give better gas mileage. I can see why in city driving larger tires would suck because of constant braking and accelerating.

I'm trying to research why larger tires would decrease a car's mpg even though larger tires can travel a greater distance with each rotation of the axle. Most of the reasons given on the internet claim the added weight of a larger tire will cause the lower mpg. This doesn't seem like a very good reason since the added weight of larger tires would be insignificant compared to the weight of the car. Also, tire/wheel weight can be manipulated by changing width and using more expensive and lighter materials. There has to be another reason. Could it be that the force a larger tire puts on the road is less than the force a smaller tire puts on the road (with an axle of equal size)? I'm hypothesizing that because the torque of the axle, a small tire and a larger tire should be the same but the force from their edge would be different. (Torque = Force x radius)