Consider four sealed, rigid containers with the following volumes: 50 ml, 100 ml, 250 ml, and 500 ml. if each of these contains .25 moles of helium gas at standard temperature, which container would have the greatest pressure?

First, we assume that helium behaves as an ideal gas such that the ideal gas law is applicable.
                                     PV = nRT
where P is pressure, V is volume, n is number of moles, R is universal gas constant, and T is temperature. From the equation, if n, R, and T are constant, there is an inverse relationship between P and V. From the given choices, the container with the greatest pressure would be the 50 mL. 

Spontaneity tell us the direction of the reaction, but not how fast it goes. gibbs free energy brings together enthalpy, entropy and temperature in one easy formula. g = h - ts. and, finally the sign of delta g is always negative for a spontaneous reaction.