Salt water can be desalinated by distillation. How much energy is needed to convert 175 g of salt water at 28.0 °C to water vapor if the specific heat of salt water is 5.19 J/g K, the boiling point of salt water is 102.5 °C, and the enthalpy of vaporization is 2.26 kJ/g?

A. 317 kJ
B. 399 kJ
C. 463 kJ
D. 512 kJ
E. 673 kJ

Explanation:

Hello,

In this case, we find the following states:

a. Liquid salt water at 28.0 °C.

b. Liquid salt water at 102.5 °C.

c. Vapor salt water at 102.5 °C.

The first process (1) is to heat the liquid water from 28.0 °C to 102.5 °C and the second one (2) to vaporize the liquid salt water. In such a way, each process has an amount of energy that when added, yields the total energy for the process as shown below:

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definition

                    entropy is a measure of the randomness or the extent of disorder of a chemical process.

                      enthalpy is a measure of the heat change of a reaction occurring at a constant pressure.

measurement units:

                        entropy is measured in joule per kelvin (jk⁻¹)   whereas enthalpy is measured in joule per mole (jmol⁻¹)

requirements:

                            entropy has no requirements or limits, and its change is measured by the division between the heat change of the chemical process and the temperature.

                              in contrast, enthalpy can only be related to the heat change of the reaction under standard conditions.