Question

Because of the pressure inside a popcorn kernel, water does not vaporize at 100°C. Instead, it stays liquid until its temperature is about 175°C, at which point the kernel ruptures and the superheated water turns into steam. How much energy is needed to pop 95.0 g of corn if 12 percent of a kernel's mass consists of water: Assume that the latent heat of vaporization of water at 175°C is 0.90 times its value at 100°C and that the kernels have an initial temperature of 175°C.

Answer 1

The energy needed to pop 95.0 g of corn is approximately 5.2 kJ.

First, calculate the mass of water in the kernels:

Mass of water = 95.0 g x 0.12 = 11.4 g

Next, calculate the latent heat of vaporization of water at 175°C:

Latent heat of vaporization = 0.90 x 2256 kJ/kg = 2030 kJ/kg

Finally, calculate the energy needed to pop the kernels:

Energy needed = (11.4 g x 2030 kJ/kg) / 1000 = 5.2 kJ