If a solution is diluted to 200 mL of a 0.15 M solution, how much of the original 0.75 M solution was needed?

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.

It is 4.92 e-4 sorry if i am wrong