Final answer:
The number of joules released when a substance changes from gas to liquid at its boiling point can be calculated using the formula: Heat released = mass imes heat of vaporization.
Step-by-step explanation:
The heat of vaporization is the amount of heat energy required to change a substance from liquid to gas at its boiling point. In this case, the heat of vaporization is given as 1,344 J/g.
To find the number of joules released when 40 g changes from gas to liquid at 100°C, we need to use the formula:
Heat released = mass imes heat of vaporization
Using the given values, we have:
Heat released = 40 g imes 1,344 J/g = 53,760 J
Therefore, the number of joules released is 53,760 J.
Learn more about Calculating heat released during a phase change