How many of the following processes would you expect to be spontaneous at 298K and 1atm?

dissolving sugar in water
decomposing NaCl to the elements
climbing a mountain
H2O (l)------H2(g)+O2(g)

Choose one answer.
a. 0
b. 1
c. 2
d. 3
e. 4

I thought that it might be 3 of the following above because climbing a mountain is not a spontaneous process.

I don't know if the prof expects you to make an educated guess from what you know or to apply thermodynamics to determine the answer. At any rate, you are right that climbing a mountain is not spontaneous. Do you expect H2O to spontaneously decompose to H2 gas and O2 gas? I think electrolysis (electrical energy) must be applied to do that. And does NaCl spontaneously decompose to the elements Na and Cl2. Again, I think energy is required to do that.

To determine the spontaneity of a process, we can consider the change in Gibbs free energy (∆G).

If ∆G is negative, the process is spontaneous. If ∆G is positive, the process is non-spontaneous. If ∆G is zero, the process is at equilibrium.

Let's analyze each process:

1. Dissolving sugar in water:
Dissolving sugar in water is an exothermic process, meaning it releases energy. Since sugar dissolves readily in water, this process is generally spontaneous. Therefore, process 1 is expected to be spontaneous at 298K and 1atm.

2. Decomposing NaCl to the elements:
Decomposing NaCl to the elements requires breaking the ionic bonds in NaCl, which requires an input of energy. Therefore, this process is non-spontaneous under standard conditions.

3. Climbing a mountain:
Climbing a mountain is an uphill process that requires an input of energy. Therefore, this process is non-spontaneous.

4. H2O (l) → H2(g) + O2(g):
The decomposition of liquid water into its gaseous components requires an input of energy. This process is non-spontaneous in the absence of an external energy source.

Therefore, of the four processes listed, the only one expected to be spontaneous at 298K and 1atm is dissolving sugar in water.

So the correct answer is: a. 0

To determine which processes would be spontaneous at 298K and 1atm, we can use the concept of Gibbs Free Energy (ΔG). For a spontaneous process, ΔG must be negative.

Let's go through each process and analyze:

1. Dissolving sugar in water: This process involves the breaking of intermolecular forces between the sugar molecules and the water molecules. Since this process occurs readily, it is spontaneous. ΔG is negative.

2. Decomposing NaCl to the elements: Decomposition of NaCl into its elements (sodium and chlorine) would require an input of energy. So this process is not spontaneous. ΔG is positive.

3. Climbing a mountain: Climbing a mountain involves performing work against gravity. Work requires energy input, so it is not spontaneous. ΔG is positive.

4. H2O (l)------H2(g) + O2(g): This represents the process of water splitting into its constituent gases, hydrogen gas, and oxygen gas. As water splitting requires the input of energy, it is not spontaneous. ΔG is positive.

Therefore, out of the four processes listed, only one process (dissolving sugar in water) is spontaneous at 298K and 1atm. So the correct answer would be (b) 1.