Light and photons
Dimensional analysis
Concentrations
Electron Configuration
Ions and Compounds
100
When dentists take X-rays of your jaw, they give you a protective lead shield to protect you from excess radiation. How much more energy is there per photon from an X-ray (λ = 71.2 pm) than from UV radiation (λ = 250 nm)?
Energy for xray photon = 3e-15 J
Energy for UV photon = 7.96e-19 J
The difference is = 3e-15 J
100
The distance between Los Angeles and New York City is 2789.4 mi. Convert this to ft and give your answer in scientific notation with 3 sig figs.
1 mi = 5280 ft
1.47e7 ft
100
You start out with 3 M solution with 40 mL, you add 60 mL, what is the final concentration?
1.2 M
100
What is the electron configuration of As3-. Why would this be 3- instead of 2-.
Kr wants to fill the octet
100
What is the name of (C2H3O2)-
Acetate
200
Determine which of the following statements are false and correct them:
a) The frequency of radiation increases as the wavelength increases.
b) Electromagnetic radiation travels through a vacuum at constant speed, regardless of wavelength.
c) Infrared light has higher frequencies than visible light.
a. False As the wavelength decreases
b. True
c. False It has lower frequency (see electromagnetic spectrum)
200
A student wonders whether a piece of jewelry is made of pure silver. She determines that its mass is 3.17 g. Then she drops it into a 10 mL graduated cylinder partially filled with water, and determines that its volume is 0.3 mL. Could the jewelry be made of pure silver density of silver = 10.49 g/cm3
yes because the density of the object is 10.57g/cm3 that is very close to silver = 10.49 g/cm3
200
You are given 50 g of NaCl how much water should you add for a 0.08 M solution.
10.7 L
200
What is the Zeff of the following:
C and K
C: 4
K: 1
200
Tell me a possible salt with carbonate
Anything with CO3 2-
300
A stellar object is emitting radiation at 2.85 cm.
a) What is the energy of 1 photon of this radiation?
b) If a detector is capturing 6.9 x 109 photons per second at the wavelength given above, what is the total energy of photons detected in 1 hour?
a. 6.98e-24 J (pay attention to the units!!)
b. 1.73e-10 J per hour
300
You have 20 grams of CaCl2. How many Cl atoms do you have?
2.17e23 cl atoms
300
omn A yellow dye solution is spectroscopically investigated starting with a stock solution with a concentration of 35uM.
a. If the stock solution has an absorbance of 0.742 at a wavelength of 430nm, what is the molar absorptivity at this wavelength? (include proper units in your answer and assume the path length is 1 cm)
b. If the stock solution is diluted by a factor of 10, what is the absorbance of this new solution at the same wavelength of 430nm? Do you need molar absorptivity to calculate this? Why or why not?
a. 21200 M-1cm-1
b. 0.0742 and no
300
Which atom has the electron configuration 1s22s22p63s23p64s23d104p65s24d2
Zr
300
What is the difference between ionic and covalent? Which is stronger? Give and example of both.
Ionic is the transfer of electrons and covalent is the sharing. Ionic is stronger.
400
Emission of a 1282 nm photon lowers an electron in hydrogen from n=5 to which quantum number, n?
4.61 but could be wrong idk
400
True of False 35.45 grams NaCl contain the same amount of Cl atoms as 35.45 g of HCl
False HCl has more
400
0.133 mol
400
What would make K isoelectronic with Ar?
K+
400
What is wrong with this salt: Al(SO4)
What is also the name of this salt
aluminum sulfate
Al2(SO4)3
500
A nitrogen gas laser pulse with a wavelength of 337 nm contains 3.83 mJ of energy. How many photons does this laser pulse contain?
3.83 mJ = 0.00383J
Energy per photon = 5.9e-19 J/photon
0.00383 J x 1photon/5.9e-19J = 6.49e15 photons
500
According to the International Energy Agency (IEA), global energy-related carbon dioxide emissions hit
an historic high in 2017 of 32.5 gigatons (1 giga = 109). Express this mass of CO2 in moles, first with
exponential notation and then without exponential notation using an appropriate metric prefix (which
you’ll need to look up).
1ton = 907.185 Kg
2.26e15 mol
500
When cleaning a laboratory, you find a bottle with a label reading “Yellow dye, ϵ at lambda max = 1.07x104 (cm-1⋅M-1)”. When 7.6 mg is dissolved in 319 mL, an absorbance at lambda max of 0.779 was found. What is the molecular weight of the mystery dye? To answer this question you just need to think about the meaning of the molar mass of the molecules of yellow dye, that is the mass of 1 mole of yellow dye molecules.
327.59 g/mol
500
Based on their positions in the periodic table, predict which has the largest first ionization energy: Mg, Ba, B, O, Te.
O
500
Which atom and/or ion is (are) isoelectronic with Br+: Se2+, Se, As–, Kr, Ga3+, Cl–
Se, As−