EXAM 4 CHEM EXPECTED QUESTIONS WITH VERIFIED
ANSWERS
Question 1.
Yellow light given off by a sodium vapor lamp has a wavelength of 589 nm. What is the frequency of
this light?
ANSWER
589-
nm*1m/1*10^9nmmn=5.89*10-7
V=c/
λ=2.998*10^8-
m*s^-1/5.89*10^-7m=5.089*10^142^-1
or (5.09*10^14s^-1)
Question 2.
An FM radio station broadcasts at a frequency of 103.4 MHz (1 MHz = 106 s-1). Calculate the
wavelength of this radiation.
ANSWER
2.998*10^8-
m*s^-1/1.034*10^8s^-1=2.899m
103.4-
mhz*1*10^6s^-1/1mhz2=1.034*10^8s^-1
Question 3.
Calculate the energy of one photon of yellow light that has a wavelength of 589 nm.
ANSWER
V=c/. Λ=5.09*10^14s^-1
E=(6.626*10^-34j*s)(5.09*10^14*s^-1=3.37*10^-19j/photon
Question 4.
A laser emits light that has a frequency of 4.69 x 1014 s-1. i)
ANSWER
E=(6.636*10^-34j*s)(4.69*10^14s^-1=3.11*10^-19j
,Question 5.
ii) If the laser emits a pulse containing 5.0 x 1017 photons of this radiation, what is the total energy
of that pulse?
ANSWER
Question 6.
If the laser emits 1.3 x 10-2 J of energy during a pulse, how many photons are emitted?
ANSWER
Question 7.
What is the energy of one photon of this radiation?
ANSWER
i. Etot=(5.0*10^17pho-
ii. tons)(3.11*10^-19j/pjo-
iii. ton)=0.155
,Question 8.
Consider only the transitions involving the first four energy levels for a hydrogen atom.
ANSWER
How many emissions are
possible for an electron in the
n=4 level as it goes to the
ground state?=i) 3 emission
ii) Which electronic tran-
sition is the lowest ener-
gy?n=4>n=3
iii) Which electronic transition
corresponds to the shortest
wavelength emission?=high
freq.n=4>n=1
Question 9.
Calculate the wavelength of light emitted when the n=3 n=2 transition occurs in a hydrogen atom.
What ö type of electromagnetic radiation is emitted?
ANSWER
, Question 10.
Calculate the wavelength of light emitted when the n=2 n=1 transition occurs in a hydrogen atom.
What ö type of electromagnetic radiation is emitted?
ANSWER
Question 11.
Calculate the wavelength of a golf ball with a mass of 45.9 g moving at a speed of 50.0 m/s.
ANSWER
6.626*10^-34j*s/45.9g
*50m*s^-1*1
kg*m^2/s^2*1000g/kg
=2.89*10^-34m
Question 12.
What is the wavelength of an electron moving with a speed of 5.97 x 10^6 m/s? The mass of the
electron is 9.11 x 10 kg
ANSWER
6.626-
x10^-34j*s/9.11*10^-31kg x 5.97x10^6m/s^-*kg*m^@/s^2
1.22x10^-10m
0.122nm
Question 13.
light can behave like a particle, can matter behave like a wave?
ANSWER
ANSWERS
Question 1.
Yellow light given off by a sodium vapor lamp has a wavelength of 589 nm. What is the frequency of
this light?
ANSWER
589-
nm*1m/1*10^9nmmn=5.89*10-7
V=c/
λ=2.998*10^8-
m*s^-1/5.89*10^-7m=5.089*10^142^-1
or (5.09*10^14s^-1)
Question 2.
An FM radio station broadcasts at a frequency of 103.4 MHz (1 MHz = 106 s-1). Calculate the
wavelength of this radiation.
ANSWER
2.998*10^8-
m*s^-1/1.034*10^8s^-1=2.899m
103.4-
mhz*1*10^6s^-1/1mhz2=1.034*10^8s^-1
Question 3.
Calculate the energy of one photon of yellow light that has a wavelength of 589 nm.
ANSWER
V=c/. Λ=5.09*10^14s^-1
E=(6.626*10^-34j*s)(5.09*10^14*s^-1=3.37*10^-19j/photon
Question 4.
A laser emits light that has a frequency of 4.69 x 1014 s-1. i)
ANSWER
E=(6.636*10^-34j*s)(4.69*10^14s^-1=3.11*10^-19j
,Question 5.
ii) If the laser emits a pulse containing 5.0 x 1017 photons of this radiation, what is the total energy
of that pulse?
ANSWER
Question 6.
If the laser emits 1.3 x 10-2 J of energy during a pulse, how many photons are emitted?
ANSWER
Question 7.
What is the energy of one photon of this radiation?
ANSWER
i. Etot=(5.0*10^17pho-
ii. tons)(3.11*10^-19j/pjo-
iii. ton)=0.155
,Question 8.
Consider only the transitions involving the first four energy levels for a hydrogen atom.
ANSWER
How many emissions are
possible for an electron in the
n=4 level as it goes to the
ground state?=i) 3 emission
ii) Which electronic tran-
sition is the lowest ener-
gy?n=4>n=3
iii) Which electronic transition
corresponds to the shortest
wavelength emission?=high
freq.n=4>n=1
Question 9.
Calculate the wavelength of light emitted when the n=3 n=2 transition occurs in a hydrogen atom.
What ö type of electromagnetic radiation is emitted?
ANSWER
, Question 10.
Calculate the wavelength of light emitted when the n=2 n=1 transition occurs in a hydrogen atom.
What ö type of electromagnetic radiation is emitted?
ANSWER
Question 11.
Calculate the wavelength of a golf ball with a mass of 45.9 g moving at a speed of 50.0 m/s.
ANSWER
6.626*10^-34j*s/45.9g
*50m*s^-1*1
kg*m^2/s^2*1000g/kg
=2.89*10^-34m
Question 12.
What is the wavelength of an electron moving with a speed of 5.97 x 10^6 m/s? The mass of the
electron is 9.11 x 10 kg
ANSWER
6.626-
x10^-34j*s/9.11*10^-31kg x 5.97x10^6m/s^-*kg*m^@/s^2
1.22x10^-10m
0.122nm
Question 13.
light can behave like a particle, can matter behave like a wave?
ANSWER
