Chemistry, 14.06.2021 16:00 kbuhvu

(A) Calculate the wavelength (in nm) of light with energy 1.89 × 10–20 J per photon, (b) For light of wavelength 410 nm, calculate the number of photons per joule, (c) Determine the binding energy (in eV) of a metal if the kinetic energy possessed by an ejected electron [using one of the photons in part (b)] is 2.93 × 10–19 J.

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Answer from: Mrcastaway3036

For A: The wavelength of the light is $1.052\times 10^4nm$

For B: The number of photons per joule is $2.063\times 10^{18}$

For C: The binding energy of a metal is 1.197 eV.

Explanation:

The equation used to calculate the energy of a photon follows:

$E=\frac{hc}{\lambda}$ ......(1)

where,

E = energy of a photon

h = Planck's constant = $6.626\times 10^{-34}J.s$

c = speed of light = $3\times 10^{8}m/s$

$\lambda$ = wavelength

For A:

Given values:

E = $1.89\times 10^{-20}J$

Putting values in equation 1, we get:

$\lambda=\frac{(6.626\times 10^{-34}J.s)\times (3\times 10^8m/s)}{1.89\times 10^{-20}J}\\\\\lambda=1.052\times 10^{-5}m$

Converting the wavelength into nanometers, the conversion factor used is:

1m=10^9nm

So, $\lambda=1.052\times 10^{-5}m\times \frac{10^9nm}{1m}=1.052\times 10^4nm$

Hence, the wavelength of the light is $1.052\times 10^4nm$

For B:

Given values:

$\lambda=410nm=410\times 10^{-9}m$

Putting values in equation 1, we get:

$E=\frac{(6.626\times 10^{-34}J.s)\times (3\times 10^8m/s)}{410\times 10^{-9}m}\\\\E=4.848\times 10^{-19}J$

To calculate the number of photons, we use the equation:

$\text{Number of photons}=\frac{\text{Total energy}}{\text{Energy of a photon}}$

Total energy = 1 J

Energy of a photon = $4.848\times 10^{-19}J$

Putting values in the above equation:

$\text{Number of photons}=\frac{1J}{4.848\times 10^{-19}J}\\\\\text{Number of photons}=2.063\times 10^{18}$

Hence, the number of photons per joule is $2.063\times 10^{18}$

For C:

To calculate the binding energy of a metal, we use the equation:

E=K+B .....(2)

E = Total energy

K = Kinetic energy of a photon

B = Binding energy of metal

Converting the energy from joules to eV, the conversion factor used is:

$1eV=1.602\times 10^{-19}J$

Using the above conversion factor:

$K=2.93\times 10^{-19}J=1.829eV\\\\E=4.848\times 10^{-19}J=3.026eV$

Putting values in equation 2:

B=(3.026-1.829)eV=1.197eV

Hence, the binding energy of a metal is 1.197 eV.

Answer from: Quest

Answer: abeexplanation:

1. the question asks the most appropriate, which seems to rule out "all of the above." your choice appears to be the correct one.

2. the protocol described is good for identifying correlation, but not cause and effect. for cause/effect, you need to devise a protocol that will assign the treatment (or not) to groups that have essentially the same "demographics" with respect to all the other variables. your choice regarding control group seems appropriate. random assignment of treatment (choice d) may be appropriate also. (i think you can argue that b and d are just different descriptions of the same method.)

3. d will randomize the birds, but may not guarantee there are 10 in each group. e will do both, so seems the better choice.

comment on question 2

based on the problem statement, it seems clear that confident, attentive drivers are more likely to use daytime running lights. so, the protocol might need to be devised in such a way that the lights would be turned on or off without the driver's knowledge. (an attentive driver will figure it out.) assigning a confident, attentive driver to a group required to drive without running lights might mess with his/her confidence and attentiveness. you don't want your experiment to do that. (nor do you want the experiment to subject a driver to greater risk of accident as a consequence of driving without running lights.) experiments involving human safety are always problematic.

Answer from: Quest

is there any options? maybe im just not seeing them but i need the options to

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