Final answer:
To completely evaporate 25 g of water at 100°C, 56,250 joules of energy are needed.
Step-by-step explanation:
To completely evaporate 25 g of water at 100°C, we need to calculate the amount of heat required using the specific heat formula:
Heat = mass × specific heat × temperature change
Given that the heat of vaporization of water is 2250 J/g, we can substitute the values into the formula:
Heat = 25 g × 2250 J/g × (100°C - 0°C)
Heat = 56,250 J
Therefore, 56,250 joules of energy are needed to completely evaporate 25 g of water at 100°C.