In: Chemistry
Calculate the wavelengths (in nm) of the first 5 transitions in the Balmer series using the Rydberg equation. Convert the wavelengths calculated into frequencies.
Balmer series --> n = 2 so
n3 --> 2
n4 --> 2
n5 --> 2
N6 --> 2
n7 --> 2
Apply Rydberg Formula
E = R*(1/nf^2 – 1/ni ^2)
R = -2.178*10^-18 J
Nf = final stage/level
Ni = initial stage/level
E = Energy per unit (i.e. J/photon)
For the wavelength:
WL = h c / E
h = Planck Constant = 6.626*10^-34 J s
c = speed of particle (i.e. light) = 3*10^8 m/s
E = energy per particle J/photon
WL = wavelength in meters
simplified:
WL = (6.626*10^-34 )(3*10^8) / ((2.178*10^-18) * (1/nf^2 – 1/ni ^2)) * 10^9
since nf = 2, then
WL = (6.626*10^-34 )(3*10^8) / ((2.178*10^-18) * (1/2^2 – 1/ni ^2)) * 10^9
n = 3,4,5,6,7,
WL = (6.626*10^-34 )(3*10^8) / ((2.178*10^-18) * (1/2^2 – 1/3^2)) * 10^9 = 657 nm
WL = (6.626*10^-34 )(3*10^8) / ((2.178*10^-18) * (1/2^2 – 1/4^2)) * 10^9 = 487 nm
WL = (6.626*10^-34 )(3*10^8) / ((2.178*10^-18) * (1/2^2 – 1/5^2)) * 10^9 = 434 nm
WL = (6.626*10^-34 )(3*10^8) / ((2.178*10^-18) * (1/2^2 – 1/6^2)) * 10^9 = 410 nm
WL = (6.626*10^-34 )(3*10^8) / ((2.178*10^-18) * (1/2^2 – 1/7^2)) * 10^9 = 398 nm
change to frequency
v(3) = c/WL*10^9 = (3*10^8)*(10^9)/(657 )= 4.56*10^14 Hz
v(4) = c/WL*10^9 = (3*10^8)*(10^9)/(487 )= 6.16*10^14 Hz
v(5) = c/WL*10^9 = (3*10^8)*(10^9)/(434 )= 6.91*10^14 Hz
v(6) = c/WL*10^9 = (3*10^8)*(10^9)/(410 )= 7.32*10^14 Hz
v() = c/WL*10^9 = (3*10^8)*(10^9)/(398)= 7.54*10^14 Hz