If you had observed the fate of an ice cube at 25 degrees Celsius, what would you conclude about the spontaneity of the process H2O (s) <-> H2O (l) ?
I know for it to be spontaneous, delta G has to be negative, but how can I determine the delta G with the info given in the question?
I don't think the question is asking you to determine dGrxn. I think the question is asking, "Is the rxn spontaneous or not?" and the answer is yes it is. If you look at dStotal = dSsurr + dSrxn
dSrxn is + since liquid H2O has higher entropy than solid H2O and dsurroundings is q/T so dStotal is + and that means the reaction is spontaneous.
To determine the spontaneity of the process H2O (s) <--> H2O (l), you cannot directly calculate the value of delta G with the information given in the question. The question only provides the temperature, which is 25 degrees Celsius.
However, you can make an inference based on the given information. At 25 degrees Celsius, water typically exists as a liquid phase under standard conditions. Since the ice is at 25 degrees Celsius, it means that it has reached its melting point and is in the process of melting into liquid water.
The melting of ice into liquid water is a spontaneous process because it occurs naturally without any external input of energy. Consequently, the process H2O (s) <--> H2O (l) is considered thermodynamically favorable or spontaneous at this temperature.
Keep in mind that while this inference holds generally at 25 degrees Celsius, it may not be true for different temperatures, pressures, or other conditions. The spontaneity of a process can be better determined by calculating the change in Gibbs free energy, delta G, using the equation delta G = delta H - T delta S, where delta H is the change in enthalpy, T is the temperature in Kelvin, and delta S is the change in entropy.
To determine the spontaneity of the process H2O (s) <-> H2O (l), you need to consider the temperature at which the observation was made.
If an ice cube is observed at 25 degrees Celsius, it is important to note that this temperature is above the freezing point of water, which is 0 degrees Celsius. At 25 degrees Celsius, water exists naturally in the liquid phase.
Given this information, we can conclude that the process H2O (s) <-> H2O (l) is not spontaneous at 25 degrees Celsius. Since the ice cube has already melted into liquid water, it indicates that the forward reaction (melting of the ice) is occurring, not the reverse reaction (freezing of water to form ice).
However, it is important to note that this observation alone does not provide a direct way to determine the value of ΔG. Additional information, such as the entropy change (ΔS) and the temperature (T), would be necessary to calculate ΔG using the equation ΔG = ΔH - TΔS, where ΔH is the enthalpy change.
In summary, based on the observation of an ice cube at 25 degrees Celsius, it can be concluded that the process H2O (s) <-> H2O (l) is not spontaneous at this temperature.