At high altitudes, the ambient air pressure can be significantly less than 1 bar, so water boils at a lower temperature than 100 C. What is the boiling point of water at an altitude where the ambient air pressure is 0.72 bar? The enthalpy of vaporization of water near its boiling point is 40.7 kJ/mol.

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Abigailf91er · Accepted Answer

Given:Normal boiling point of water   =      100    ∘    =  373     KPressure at boiling point  = 760 mmHgPressure at altitude = 0.72 bar = 540 mmHgEnthalpy of vaporization of water near its boiling point = 40.7 kJ/mol.Calculation for pressure at altitude:  ln  ⁡  (            P      2              P      1        )  =  −            △              H                  v          a          p                      R    (      1          T      2        −      1          T      1        )    ln  ⁡  (      540    760    )  =            −      40.7      ×              10        3              8.314    ×  (      1          T      2        −      1          373             K        )    0.3417  =  −  4895.36     m  o  l  .  K  ×  (      1          T      2        −      1          373             K        )    6.98  ×      10          −      5        +      1          373             K        =      1          T      2              T    2    =      1          2.757      ×              10                  −          3                                   K                  −          1                            T    2    =  363.5     K  =      90.5    ∘    CThe boiling point of water at an altitude where the ambient air pressure is 0.72 bar is 90.5 C.

At high altitudes, the ambient air pressure can be significantly less than 1 bar, so water boils at

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