`DeltaH=30kJmol^(-1), DeltaS=75J//K//mol.
"find boiling temperature at" 1atm: `

Options

A. 400K
B. 300K
C. 150 K
D. 425 K

Explanation

To find the boiling temperature at 1 atm given the values of ΔH and ΔS, we can follow these steps:

### Step-by-Step Solution:

1. **Understand the Conditions**: At the boiling point, the system is in equilibrium, which means that the Gibbs free energy change (ΔG) is equal to zero.

2. **Use the Gibbs Free Energy Equation**: The relationship between ΔG, ΔH, and ΔS is given by the equation:
\[ \Delta G = \Delta H - T \Delta S \]
At the boiling point, we set ΔG to zero:
\[ 0 = \Delta H - T \Delta S \]

3. **Rearrange the Equation**: Rearranging the equation gives us:
\[ T \Delta S = \Delta H \]
Therefore, we can solve for T:
\[ T = \frac{\Delta H}{\Delta S} \]

4. **Substitute the Values**: We have the following values:
- ΔH = 30 kJ/mol = 30,000 J/mol (since 1 kJ = 1000 J)
- ΔS = 75 J/K·mol

Now substituting these values into the equation:
\[ T = \frac{30,000 \, \text{J/mol}}{75 \, \text{J/K·mol}} \]

5. **Calculate the Temperature**: Perform the division:
\[ T = 400 \, \text{K} \]

6. **Conclusion**: The boiling temperature at 1 atm is 400 K.

### Final Answer:
The boiling temperature at 1 atm is **400 K**.