An ice cube floats in your glass of water, just as an iceberg floats in the ocean. What conclusion can you draw about the density of liquid water and the density of solid water?

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.