Which of the following is an example of a chemical change? a. freezing water to make ice.
b. a firework exploding.
c. breaking a glass bottle.
d. melting gold jewelry to make a gold bar.

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.

What are the options? i can you if you give them.

You would do 1500/4 and the answer is 375