JEE MAIN - Chemistry (2022 - 24th June Evening Shift - No. 2)

The energy of one mole of photons of radiation of wavelength 300 nm is

(Given : h = 6.63 $$\times$$ 10$$-$$34 J s, NA = 6.02 $$\times$$ 1023 mol$$-$$1, c = 3 $$\times$$ 108 m s$$-$$1)
235 kJ mol$$-$$1
325 kJ mol$$-$$1
399 kJ mol$$-$$1
435 kJ mol$$-$$1

Explanation

Energy of one photon

$$E = {{1240} \over {\lambda (nm)}}eV$$

$$ = {{1240} \over {300}}$$

$$ = 4.1333\,eV$$

$$\therefore$$ Energy of one mole of photon

$$ = 4.1333 \times 6.02 \times {10^{23}}\,eV$$

$$ = 4.1333 \times 6.02 \times {10^{23}} \times 1.6 \times {10^{ - 19}}\,J$$

$$ = {{4.1333 \times 6.02 \times {{10}^{23}} \times 1.6 \times {{10}^{ - 19}}} \over {1000}}\,kJ$$

$$ = 399\,kJ/mol$$

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