It's been a while since I've taken general chemistry, and I'm looking back at some questions and the information I need for this one isn't coming back to me. The question reads.
What is the wanelength, in nm, of radiation that has an energy content of 1000 kJ/mol?
If anyone can give me a hand with this one, I would greatly appreciate it. Thanks.
2006-10-28 07:58:53 · 4 answers · asked by Anonymous in Science & Mathematics ➔ Chemistry
6.6261 x 10^-34 Joule seconds is Planck's constant.
This is what you need, along with maybe the speed of light, c=3x10^8m/s (not exact).
Now the speed of light is equal the product of the wavelength and frequency.
You are given 1000 kJ per mole of quanta. One mole is 6.02 x 10^23 quanta. So each one is 10^6 J/6.02 x 10^23.
Divide by h (plank's constant), 6.6261 x 10^-34 Jsec to get reciprocal seconds (frequency).
Divide speed of light by this frequency to get wavelength. Convert to nanometers by division by 10^-9.
2006-10-28 08:11:40 · answer #1 · answered by Anonymous · 0⤊ 0⤋
First find the energy of one quantum - one photon - of energy. One mole of photons equals 6.02x10^23 photons, so:
E = 1000x10^3/6.02x10^23 J or E = 1.66x10^(-18) J approx.
Now E = h*f, where h = 6.63x10^(-34) J*s the Planck constant and f the frequency of the radiation. Solve for f:
f = E/h, f = 1.66x10^(-18)/6.63x10^(-34), f = 2.5x10^15 Hz
If c = 3x10^8 m/s the speed of light then: c = l*f, where l the wavelength. Solve for λ:
l = c/f, l = 3x10^8/2.5x10^15, l = 1.2x10^(-7) m or
l = 120 nm
2006-10-28 15:19:34 · answer #2 · answered by Dimos F 4 · 0⤊ 0⤋
Energy = h * c / wavelength
Where h is planck's constant and c the speed of light. Plug the numbers in. Watch the units!
2006-10-28 15:13:29 · answer #3 · answered by Dr. J. 6 · 0⤊ 0⤋
im sorry i forgot
2006-10-28 15:02:05 · answer #4 · answered by Anonymous · 0⤊ 0⤋