For a spontaneous reaction, `DeltaG` should be :

Options

A. positive
B. negative
C. equal to zero
D. may be positive or negative

Answer

To determine the value of `Delta G` for a spontaneous reaction, we can follow these steps:

### Step-by-Step Solution:

1. **Understand the Gibbs Free Energy Equation**:
The Gibbs free energy change (ΔG) for a reaction is given by the equation:
\[ \Delta G = \Delta H - T \Delta S \]
where:
- ΔH = change in enthalpy (heat content)
- T = temperature in Kelvin
- ΔS = change in entropy (disorder)

2. **Identify the Conditions for Spontaneity**:
A reaction is considered spontaneous if it can occur without any external influence. The spontaneity of a reaction is determined by the sign of ΔG:
- If ΔG < 0 (negative), the reaction is spontaneous.
- If ΔG > 0 (positive), the reaction is non-spontaneous.
- If ΔG = 0, the system is at equilibrium.

3. **Analyze the Implications of ΔG**:
- A negative ΔG indicates that the process releases free energy, leading to a more stable state. This is analogous to a ball rolling down a hill; it moves spontaneously to a lower energy state.
- Conversely, a positive ΔG means that the process requires energy input to proceed, thus it is not spontaneous.

4. **Conclusion**:
For a spontaneous reaction, the value of ΔG must be negative. Therefore, the correct answer to the question is that ΔG should be negative.

### Final Answer:
For a spontaneous reaction, `Delta G` should be negative.

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