## Chemistry and Chemical Reactivity (9th Edition)

Energy required: $11\ g\times 4.0\ J/g.K\times 3.0\ K=132\ J$ Energy per photon: $E=h\times c/\lambda$ $E=6.626\times10^{-34}\ J.s\times2.998 \times10^8\ m/s\div 0.12\ m=1.66\times10^{-24}\ J$ Number of photons: $132\ J\div1.66\times10^{-24}\ J/photon=8.0\times10^{25}\ photons\approx 132\ mol$