Mass percentage of sodium chloride(NaCl) in ocean waters = 3.5 %
That means 3.5 g sodium chloride(NaCl) is present for every 100 g of ocean water.
The given mass of sodium chloride(NaCl) is 45.8 g
Calculating the mass of ocean waters that would contain 45.8 g sodium chloride(NaCl):

= 1309 g ocean water
Therefore, 45.8 g sodium chloride is present in 1309 g ocean water.
Since the enthalpy can be calculated from the heat of formation, the enthalpy is 136 kJ/mol.
<h3>What is enthalpy?</h3>
The enthalpy of a reaction is the heat that is lost or gained in that reaction. We know that the enthalpy can be calculated from the heat of formation.
Thus, we can obtain the enthalpy of the reaction as 4 * 34 kJ/mol = 136 kJ/mol.
Learn more about enthalpy:brainly.com/question/13996238
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