Question

Find the number of photons of wavelength = 5.49×10−6 m that must be absorbed to melt 1.00 g of ice.

Answer 1

First, we determine the energy required to melt one gram of ice. This is given by:

Energy = mass * latent heat of fusion
Energy = 1 g * 334 J/g
Energy = 334 J

Next, we use Planck's equation which is:

Energy  = number of photons * Planck's constant * speed of light / wavelength

334 = n * 6.64 x 10⁻³⁴ * 3 x 10⁸ / 5.49 x 10⁻⁶
n = 9.20 x 10²¹

9.20 x 10²¹ photons need to be absorbed by the ice.