Using ln(Psat) = A − 5000/T (Psat in atm, T in K), estimate the saturation pressure of water at 50 °C (assume A is calibrated to water so that this form is accurate near 50 °C). Choose the closest value.

Introduction / Context:
Compact Clausius–Clapeyron-type expressions are widely used to estimate saturation pressures near a reference temperature. Here, ln(Psat) = A − 5000/T represents an integrated form with constants chosen for water over a limited range. The task is to estimate Psat at 50 °C and pick the closest option.

Given Data / Assumptions:

• T = 50 °C = 323 K.
• Equation form: ln(Psat) = A − 5000/T, with A previously fitted for water in this range.
• Answers are approximate (two decimal places in atm).

Concept / Approach:
Although A is not explicitly provided, standard steam-table data state that the saturation pressure of water at 50 °C is approximately 12.3 kPa, which equals about 0.121–0.123 atm. Among the discrete options, the best match is 0.13 atm. This is consistent with the expectation from a CC-type fit over modest temperature intervals.

Step-by-Step Solution (Reasoning by Reference Values):

Verification / Alternative check:
Using ln(Psat) = A − 5000/323 and calibrating A with any one known point (e.g., at 373 K, Psat = 1 atm) yields an A value that, when used at 323 K, also produces ≈0.12 atm, consistent with the selection.

Why Other Options Are Wrong:

• 0.07 and 0.09 are characteristic of lower temperatures (≈40–45 °C).
• 0.11 underestimates the known 50 °C pressure.
• 0.20 is closer to ≈60 °C.

Common Pitfalls:
Expecting exactness from simplified correlations; always pick the closest value and remember that constants like A are fit-dependent.

Final Answer:
0.13