A single pulse of a laser yields an average of 5.00 × 10¹⁸ photons with $\lambda$ = 633 nm.If melting ice to water at 0°C requires 6.01 kJ/mol, what is the fewest number of laser pulses need to melt 10.0 g of ice? A)38300 B)3830 C)3340 D)2120 E)212

Question

Quizplus · Accepted Answer

To melt 1 mole (18.015 g) of ice, we need 6.01 kJ/mol, which is 334 J/g. Therefore, to melt 10.0 g of ice, we need:

10.0 g x 334 J/g = 3340 J

Each photon of the laser has an energy of:

E = hc/λ = (6.626 x 10^-34 J s x 3.00 x 10^8 m/s)/(633 x 10^-9 m) = 3.14 x 10^-19 J

Therefore, the number of photons needed to provide 3340 J of energy is:

n = (3340 J) / (5.00 x 10^11 photons x 3.14 x 10^-19 J/photon) = 2120

Therefore, the fewest number of laser pulses needed to melt 10.0 g of ice is 2120.

A Single Pulse of a Laser Yields an Average of 5.00