Light travels at precisely <span>299,792,458 metres every second (abbreviated to 3 x 10^8 metres every second but let's be precise) There are 60 seconds in every minute (</span><span>299 792 458 x 60 = 17,987,547,480m) 60 minutes in every hour (17,987,547,480 x 60 = 1,079,252,849,000m) 96 hours in 4 days (</span><span>1,079,252,849,000 x 96 = 10,360,827,350,000m) </span><span>Now let's convert to km to make this number (slightly) more manageable (</span>10,360,827,350,000 / 1000 = <span>103,608,273,500km) </span>Light travels <span>103,608,273,500km in 4 days - that's the equivalent of going around the equator of the earth 813,124 times!</span><span>
The formula for the self ionization of water is 2H₂O(l)⇄H₃O⁺(aq)+OH⁻(aq)
The hydronium (H₃O⁺) is usually just referred to as a hydrogen ion or a proton (H⁺) and hydroxide (OH⁻) doesn't have another name that I am aware of. These ions do stay in solution. However the concentrations are really small and the equilibrium constant (K(w)) is 1×10⁻¹⁴.
I hope this helps. Let me know if anything is unclear.
The standard emf of the voltaic cell is the value of the standard potential of it, which is calculated by the standard reduction potential (E°).
The standard reduction potential is the potential needed for the reduction reaction happen, and it's determined by the reaction with the hydrogen cell (which has E° = 0.0V). The half-reactions of reduction of Ni⁺² and Ag⁺, are:
Ni⁺²(aq) + 2e⁻ → Ni(s) E° = -0.23 V
Ag⁺(aq) + e⁻ → Ag(s) E° = +0.80 V
The value is calculated by a spontaneous reaction, in which the cell with the greater E° is reduced (gain electrons), and the other is oxidized (loses electrons). So, Ag⁺ reduces.
