General Chemistry
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Which of the following wave representations is consistent with high-energy radiation?
Calculate the energy (in kJ/mol) of each of the following photons given either the frequency or the wavelength: 1.60×1014 s−1, 2.34×1014 s−1, and 1.09×10−6 m.
Mercury exists in nature as Hg, Hg+, and Hg2+. If Hg has a second ionization energy of +1810 kJ/mol, calculate the longest possible wavelength (in nm) of light that can remove an electron from Hg+(g) to form Hg2+(g).
Potassium has a first ionization of +418.8 kJ/mol. Determine the longest possible wavelength (in nm) of light that can ionize a potassium atom.
Blue light with a wavelength of 460 nm from a 3.5 mW diode laser illuminates on a solar cell. If every photon is absorbed by the cell and every photon creates an electron, how much current (in milliamperes) passes through the solar cell's circuit?
A p-n junction in a photovoltaic cell turns solar light into electrical current. The wavelength of maximum sun intensity at the Earth's surface would be matched to the band-gap energy of an ideal semiconductor. Which semiconductor among the following absorbs at a wavelength that corresponds to the maximum solar intensity(λ=500 nm)? CdS semiconductor (band-gap energy = 241 kJ/mol) or GaAs semiconductor (band-gap energy = 138 kJ/mol)
Microwave ovens operate by exposing food to microwave radiation, which is absorbed and turned into heat. How many photons are required to raise the temperature of an 450 mL cup of water from 23.5 °C to 97.2 °C if radiation with l = 10.0 cm is used, all energy is converted to heat, and 4.184 J is required to raise the temperature of 1.00 g of water by 1.00 °C?
One watt (W) is equal to 1 J/s. How many photons are released by a light bulb every second if 4.5% of the energy produced by a 55 W light bulb is visible light and its average wavelength is 530 nm?
The most distinct lines in the atomic spectra of helium are 447.1 nm (blue line), 501.6 nm (cyan line), and 587.6 nm (yellow line). What is the energy in kilojoules per mole of each of these spectral lines?
How much energy in kilojoules does one mole of photon of visible light possess if it has a 450 nanometer wavelength?
Calculate the respective energies in kilojoules per mole of two lamps at 1875 GHz and 857 THz and identify which lamp has higher energy.
What is the energy of a single photon of radiation that has a frequency that measures 3.96 x1015 s- 1?
A 10.00 mL solution of 0.0500 M benzene absorbs light and releases 10.5 J of light with a wavelength of 300 nm. Calculate the percentage of benzene molecules that released light.
The photodissociation of ozone happens in the troposphere:
O3 + hν → O2 + O
A light with a maximum wavelength of 320 nm can initiate this reaction. Calculate the maximum bond strength (kJ/mol) that can be broken by the absorption of 320 nm light.
What is the effect of greenhouse gases on how the planet cools given that the sun provides average energy of 168 watts per square meter while the Earth's surface emits an average of 390 watts per square meter?
At altitudes below 80 km, photoionization of oxygen becomes more important than photodissociation of oxygen. Is this statement true or false?
The light energy from the sun is the main source of energy for photosynthesis. True or False?
The photodissociation of Freon-11 (CCl3F) is as follows: CCl3F + hν → Cl• + •CCl2F. What is the wavelength of photons required to initiate this reaction? [Hint: Use bond energies.]
The nitrogen-chlorine bond has an average bond dissociation energy of 200 kJ/mol. Calculate the highest wavelength of photons that can initiate the dissociation of the N–Cl bond.
Assuming that a specific tree grows about 6 ft per year, identify the statement that describes if a tree's growth was quantized in 1-ft increments:
A laser cutter can cut an acrylic board in 29.0 s. Calculate the number of photons used in cutting if the laser has a wavelength of 1064 nm and a power of 120 W.
UV light is used to initiate radical reactions in organic chemistry. For an HCl molecule, the quanta of UV light is used to break the bond between the chlorine atom and hydrogen atom. Assuming that 1 photon of a UV light with the wavelength of 280.4 nm can break one H-Cl bond, calculate the bond energy in kJ/mol.
Calculate the difference in energy of photons between a 1.5 x 1015 Hz UV light and a 3.5x1012 Hz IR light.
Lithium chloride imparts a red color to a flame. Calculate the energy of 1.00 mol of the photons involved if the wavelength of the light emitted is 670.8 nm.
A free-radical reaction is a chemical reaction that is abundant in organic reactions. Light is used to initiate the reaction by breaking bonds between atoms and forming radicals. Consider the bond in a chlorine molecule (Cl2) which takes 239 kJ/mol top break. Calculate the longest possible wavelength needed to initiate the reaction.
A ray of ultraviolet light has a wavelength of 321 nm. Calculate the energy in 1 mole of photons of this light.
The wavelength of an orange light is 586.9 nm. Calculate the energy of a photon of this light.
Calculate the wavelength of a laser that produces 35.2 mW. The laser emits 3.61 X 1021 photons in 2.31 hr.
Find the corresponding energy of a photon for each of the following frequencies:
a. 2.2 GHzb. 4.2 THzc. 102.5 MHz
Calculate the number of photons present in a laser pulse that carries 4.15 mJ of energy and has a wavelength of 487 nm.
Determine the number of photons that a compact microwave oven emits per second if the oven generates 652 watts of power using 12.24 cm wavelength electromagnetic waves. (Note: 1 watt = 1 J/s)
Calculate the percent efficiency for the conversion of power to light for a certain LED light that uses 144.0 watts of electrical power to emit 1.27×1020 535-nm photons per second.
As the energy of a photon decrease, its
Determine the longest wavelength of radiation that has enough energy to break a fluorine-fluorine bond in F2 which needs a minimum energy of 159 kJ/mol.
Calculate the energy for 1 mol of each electromagnetic radiation. Express your answer in kJ/mol
a. A wavelength of 0.149 nm for an x-ray photon
b. A wavelength of 2.45x10-5 nm for a γ-ray photon
Calculate the energy of one photon of green light if it has a frequency of 5.45x1014 Hz
When we put our hands before a fire, the warmth we feel is due to the photons of infrared radiation. Any object can be warmed by these photons. Calculate the amount of photons needed to increase the temperature of 155 grams of water from 24.0 °C to 47 °C if the wavelength of infrared photons is 1.6x10-6 m.
Which of the following statements best describes the energy of a photon?
Which photon of light in each set has the highest amount of energy?
(i) A = 7.12×1011 Hz, B = 1.33×1015 Hz, C = 2.02×1012 Hz
(ii) X = 550 nm, Y = 326 nm, Z = 428 nm
Calculate the energy (kJ) of 2.50 moles of photons for radiation with a wavelength of 295 nm within the UV region.
The dipole in an O–H polar covalent bond is a very important property of water and accounts for most of its characteristics. An O–H covalent bond requires 464 kJ/mol to break. Since this is a high-energy bond, only a wavelength of radiation within the ultraviolet region has enough energy to break this bond. Calculate the longest wavelength of radiation with enough energy to break this covalent bond.
The human eye contains a molecule called 11-cis-retinal that changes shape when struck with light of sufficient energy. The change in shape triggers a series of events that results in an electrical signal being sent to the brain that results in vision. The minimum energy required to change the conformation of 11-cis-retinal within the eye is about 164 kJ/mol. Calculate the longest wavelength visible to the human eye.
Ultraviolet radiation and radiation of shorter wavelengths can damage biological molecules because these kinds of radiation carry enough energy to break bonds within the molecules. A typical carbon–carbon bond requires 348 kJ/mol to break. What is the longest wavelength of radiation with enough energy to break carbon–carbon bonds?
The laser pointer emits light because electrons in the material are excited (by a battery) from their ground state to an upper excited state. When the electrons return to the ground state, they lose the excess energy in the form of 532-nm photons. What is the energy gap between the ground state and the excited state in the laser material?