Question

The quantum yield for decomposition of $HI$ is $0.2$. In an experiment $0.01$ moles of $HI$ are decomposed. Find the numbers of photons absorbed. $(N_A=6\times {10}^{23})$.

Answer 1

As we know that, in 1 mole of HI we have $6.022\times {10}^{23}$ number of HI molecules, then in 0.01 mole of HI we will have $=6.022\times {10}^{23}\times 0.01=6.022\times {10}^{21}$ numbers of HI molecules.

As quantum yield = Molecules decomposed / photon absorbed

photon absorbed = Molecules decomposed /quantum yield $=6.022\times {10}^{21}/0.2=3.011\times {10}^{22}$