You form water vapor by mixing oxygen and hydrogen at 730°C in a 5.4-liter container. This is the equation for the reaction:

O2(g) + 2H2(g) → 2H2O(g).

The partial pressure of oxygen before the reaction is 122.3 kilopascals, and there is excess hydrogen. How many moles of water are formed?

Consider hydrogen in an excited state n = 5n=5 that emits photons to reach the ground state. there are various possible transitions other than straight to the ground state that can occur; for example, it can drop to the n = 3n=3 state followed by the n = 3n=3 to the ground state transition. which of the possible transitions will result in the emission of a photon in the visible region?