# At temperatures above 0°C, what is the sign of the change in free energy for the conversion of liquid water to ice?

A. Positive
B. Zero
C. Negative
D. Not known

## To determine the sign of the change in free energy for the conversion of liquid water to ice at temperatures above 0°C, we can think about the process in terms of the Gibbs free energy equation. The Gibbs free energy change (∆G) is given by the equation:

∆G = ∆H - T∆S

where ∆H is the change in enthalpy, T is the temperature in Kelvin, and ∆S is the change in entropy.

In the case of the conversion of liquid water to ice, we are going from a more disordered state (liquid water) to a more ordered state (ice). This means that the change in entropy (∆S) is negative.

At temperatures above 0°C, the ∆H term (change in enthalpy) is positive because energy needs to be withdrawn from the system to convert liquid water into ice.

Since both the ∆H term and the ∆S term are negative, the overall sign of the change in free energy (∆G) is negative. Therefore, the answer is C. Negative.

To summarize, the conversion of liquid water to ice at temperatures above 0°C has a negative change in free energy.