Final answer:
The temperature of the product inside an evaporator operated at 15 in. Hg vacuum would depend on the specific substance's vapor pressure-temperature relationship and can be found using a phase diagram or table for the substance.
Step-by-step explanation:
If an evaporator is operated at 15 in. Hg vacuum, to determine the temperature of the product inside, one must refer to the vapor pressure-temperature relationship for the specific liquid being evaporated. At 15 in. Hg vacuum, this pressure translates to 29.92 - 15 = 14.92 in. Hg absolute pressure or approximately 0.507 atm. The temperature at which a liquid boils is when its vapor pressure equals the surrounding pressure. This is typically found using a temperature-vapor pressure table or a phase diagram for the specific substance.
For example, water at a pressure of 0.507 atm would boil at a temperature significantly lower than its boiling point at standard atmospheric pressure (100°C or 212°F). To provide a precise temperature for the product in the evaporator, the substance’s saturation vapor pressure information at various temperatures would be required.