Question

For light with a wavelength of 12.5 nm, determine the energy of light in kJ/mol

For any constants:
h=6.626*10^-34 j*s
c=3.00*10^8 m/s
For any conversions:
1m=10^9 nm
1J=1 kg * m^2/s^2
Kilo= 10^3

I feel like i'm on the right path but I keep getting an incorrect answer...I just want to know how to do this so I can figure out if i'm close to the right mindset.

The answer is 9570.

Answer 1

Energy is related to Wavelength as,

E = h c / λ -------- (1)
As,
h = 6.626 × 10⁻³⁴ Js
c = 2.99 × 10⁸ ms⁻¹
λ = 12.5 nm = 1.25 × 10⁻⁸ m

Putting values in eq. 1,

E = (6.626 × 10⁻³⁴ Js × 2.99 × 10⁸ ms⁻¹) ÷ 1.25 × 10⁻⁸ m

E = 1.585 × 10⁻¹⁷ J

E = 1.585 × 10⁻²⁰ kJ × 6.022 × 10²³

E = 9544.87 Kj/mol