So it's positive ten kilojoules per mole. The last thing we should mention is the mathematical formula for entropy, which basically states that change in entropy is the heat or change in energy over time, over temperature, and temperature is in Kelvin. Step one. In step one, I apply the formula for a change in entropy. That is, change in entropy surroundings is equal to change in energy over temperature, as seen here. Step two remember when we talk about free energy, or gifts free energy, we talk about a closed system, constant pressure and constant temperature.