Answers created by Truong-Son N.

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• What are the reasons why chromium and copper have half-filled #4s# orbitals?
  
• Which of the following is NOT a valid choice of #l# if #n = 4#, #m_l = 2#, and #m_s = +1/2# are already known?
  
• What is the difference between the #d_(x^2-y^2)# and #d_(xy)# orbitals of the same #n#?
  
• The rate constant of a certain reaction is given by #log_(10)k = 5.4 - 212/T#. Calculate the activation energy at #127^@ "C"#?
  
• What is the maximum number of electrons that can be in each #d# subshell?
  
• Thermochemistry help: What is the difference between.... ? Please clarify and explain.
  
• Why is #["MnI"_4]^(2-)# favored over #["MnI"_6]^(4-)#?
  
• Why is the electron-nucleus potential energy negative?
  
• What is the order of the reaction if doubling the concentration of #A# divides the half-life in 4?
  
• Calculate the ratio of catalyzed and uncatalyzed rate constant at 20 degree Celsius if the energy of activation of a catalyst reaction is 20 kilo joule per mole 4 and for an uncatalyst reaction is 75 kilo joule per mole?
  
• If a gaseous system does #"230 J"# of work on its surroundings against an external pressure of #"1.70 atm"#, to what final volume does the gas expand from #"0.300 L"#?
  
• Raw milk sours in about 4 hours at #28°C# but in about 48 hours at #5°C#. What is the activation energy (in #(kJ)/(mol)#) for the souring of milk?
  
• Which acids or bases do NOT give #"H"^(+)# upon dissolution?
  
• Order by bond length? #"NO"#, #"NO"^(+)#, #"NO"^(-)#
  
• What are two uses of sodium chloride?
  
• What is the normal boiling point for an aqueous solution containing a mol fraction of #0.35# for #"CaCl"_2#? Assume complete dissociation and #K_b = 0.512^@ "C/m"# for water.
  
• First member of a group differs from the rest of the members of the same group. Why?
  
• What do the subscripts in the wave function #psi_(nlm_l)(r,theta,phi)# indicate?
  
• How do you calculate the energy released when 24.8 g #Na_2O# reacts in this reaction: #Na_2O(s) + 2HI(g) -> 2Nal(s) + H_2O(l)#?
  
• What is the wavelength of light that hits potassium metal in order to eject photoelectrons with a wavelength of #"0.57 nm"#? The ionization energy of potassium is #"4.34 eV"#.
  
• What is the molarity for a solution with a mol fraction of #0.195# for the potassium nitrate solute? Its density is #"1.36 g/mL"#.
  
• How many possible states are there for an electron in a hydrogen atom when the principle quantum number (a) n= 1 and (b) n =2.?
  
• Where do you find formic acid?
  
• Question #35834
  
• Is #"CoCl"_4^(2-)# paramagnetic or diamagnetic?
  
• What are the Boltzmann factors?
  
• Why are tetrahedral complexes generally high spin?
  
• How do you calculate the Gibbs' free energy of mixing?
  
• How are neutrons, protons, and electrons related?
  
• What is isothermal expansion of a real gas?
  
• What is an atomic number?
  
• At #47^@"C"#, what is the average kinetic energy of #"1 g"# of #"O"_2(g)#?
  
• Why do #2d#, #1d#, and #3f# orbitals not exist?
  
• What is formal charge and how is it determined?
  
• Enthalpy question?
  
• Order pyrrolidine and piperidine by basicity?
  
• Are all polyatomic ions ionic?
  
• Explain the effects where the energy ordering between the #pi_(2p)# and #sigma_(2p)# MOs switches going from #"N"_2# to #"O"_2#?
  
• Which of these molecules has dispersion forces as its strongest intermolecular force? #"Br"_2#, #"H"_2"S"#, #"HCl"#, #"CO"#
  
• The transmittance for a sample of a solution, measured at #590nm# in a #1.5-cm# cuvette, was #76.2%#. What is the corresponding absorbance?
  
• Does pressure affect Gibbs free energy?
  
• In what region of the phase diagram would a substance certainly be a liquid? #a)# Past the triple point temperature #b)# Any spot past the melting point #c)# Between the melting point and critical temperature #d)# Between the melting and boiling points
  
• If three ideal gases collide with each other, how will the second one travel?
  
• For what temperature is the Joule-Thomson coefficient for a gas zero?
  
• How can one describe aluminum monochloride cation with a covalency model?
  
• Why does chromium form a #"Cr"^(2+)# ion?
  
• What is pyramidal inversion?
  
• Why do we say that #s# orbitals have zero angular momentum?
  
• What is the speed of an electron with a wavelength of #"0.1 nm"#? If this electron were brought up to this speed from rest, what potential difference was needed?
  
• Amy is eight years older than twice her cousin Alicia’s age. The sum of their ages is less than 32. Let x represent Alicia's age. Which inequality represents Alicia’s possible age?
  
• A stationary #He^+# ion emitted a photon corresponding to a first line of the Lyman series. The photon liberated a photoelectron from a stationary H atom in the ground state. What is the velocity of the photoelectron?
  
• A certain sports utility vehicle is traveling at a speed of #"57 mph"#. If its mass is #"5400 lbs"#, what is its de Broglie wavelength?
  
• Question #0f696
  
• If the activation energy of a reaction is zero, what does that mean for the reaction rate? What is now the only thing that it depends on that changes with temperature?
  
• If each orbital can hold a maximum of 3 electrons, the number of elements in the 4th #bb"[period of the]"# periodic table (long form) is?
  
• What is the electron capture reaction for astatine-200 in terms of the individual steps?
  
• For the reaction of #2"Al"(s)# with #3"Cl"_2(g)# to form #2"AlCl"_3(s)#, if #"20 atoms Al"# reacts with #"45 molecules"# of #"Cl"_2#, how many atoms of #"Al"# are needed to react with the excess #"Cl"_2#?
  
• Why does the reaction with #("CH"_3)_3"Br"# proceed with an #"S"_N1# and/or #"E"1# mechanism? What does it have to do with steric hindrance?
  
• Is the nonbonding orbital of #"NH"_3# a #p# orbital?
  
• What is the electron configuration of #"Na"^(+)#? How many paired electrons does it have?
  
• Compare the de Broglie wavelengths for a proton, golf ball, and alpha particle, if these have speeds of #5.81 xx 10^6 "m/s"#, #"31.3 m/s"#, and #1.52 xx 10^7 "m/s"#, respectively? Which one is a classical particle?
  
• Why is #"Co"("CN")_5^(2-)# paramagnetic?
  
• What is the density of wet air with 75% relative humidity at 1atm and 300K? Given : vapour pressure of #H_2O# is 30 torr and average molar mass of air is 29g/mol?
  
• Explain the Heisenberg Uncertainty Principle, and how the interpretation of it changes from the quantum to classical limits?
  
• How do you find first order half life?
  
• What is a single carbon molecule?
  
• What is a numerical value of the ratio of products to reactants, only at a specified temperature is called?
  
• Why does copper assume a #3d^10 4s^1# configuration if both #"Cu"^(+)# and #"Cu"^(2+)# are possible?
  
• Water can exist in each of the three states of matter (except plasma). How can you describe the volume for each state?
  
• Can someone explain to me the concept of entropy?
  
• How do I truncate this infinite series by choosing an odd #l#?
  
• How does molar conductivity relate to the salinity of a solution?
  
• The time required to finish a test is normally distributed (i.e. in a Gaussian distribution) with a mean of 60 minutes and a standard deviation of 10 minutes. What is the probability that a student will finish the test in less than 70 minutes?
  
• Given density in #"g/L"#, how to calculate molar volume?
  
• Using the MO diagram of #"NO"#, calculate the bond order. Compare it to #"NO"^(+)#?
  
• How do we know where the bonding, antibonding, and nonbonding molecular orbitals are compared to the atomic orbitals the atoms start with? Do they always interact?
  
• Why is an isothermal process slow?
  
• Arrange the following atoms in order of decreasing ionization energy? #"Cl"#, #"S"#, #"Se"#
  
• Question #b1cd1
  
• Question #8533e
  
• How is #DeltaH_(fusion)# used to calculate the mass of solid that 1kJ of energy will melt?
  
• What does a positive or negative liquid-solid slope indicate in a phase diagram?
  
• Does a mixture have to involve dissolving a solid into a different phase?
  
• For the nucleophilic aromatic substitution (NAS) reaction of 1-chloro-2,4-dinitrobenzene with methoxide in methanol, what does the intermediate look like?
  
• How does the Pauli Exclusion Principle lead to the restriction that electron with #n = 1# and #l = 0# can only take on (a linear combination of) two possible spins?
  
• You measure a piece of rope and find its length to be 12 m. How do you find the percent error of this measurement?
  
• What is the hybridization of copper in tetraamminecopper(II) in water? Why is it NOT #sp^3#, and how do you prove this using Group Theory?
  
• At a certain temperature, is an equilibrium process endothermic or exothermic, if #K < 1#?
  
• Will electrons pair up in an orbital only when all orbitals in different sub-levels have one electron?
  
• A sample of #H_2O# with a mass of 46.0 grams has a temperature of 100 °C. How many joules are necessary to boil the water? (use 2.0934 J/g for the heat of vaporization of water)
  
• Why does energy preferentially spread out in an isolated system?
  
• Noble gases are monatomic. What does monatomic mean?
  
• Can you help me please? I have a chemistry class tomorrow but I need to bring with me the answer for these two questions. So, please help. Thanks!
  
• When dissolved in water, Cu2+ often forms the complex [Cu(OH2)6]2+. What is the oxidation state of Copper?
  
• How many valence electrons do sodium and chlorine each have? What other problems can I do to practice determining things like this?
  
• Can someone help me please? I answered one of them but I would like someone to check it as well. For the other two, I honestly not sure how to do it. Thanks!
  
• Question #f5a83
  
• What are hydrides?
  
• How we combine two these equations P1V1 = k and P2 V2 = k , I need to know the combination method?
  
• If a reaction of sulfur dioxide with dioxygen gas to form sulfur trioxide starts with #"5 mols SO"_2# and #"5 mols O"_2#, and #60%# of the #"SO"_2# was consumed in the reaction, what is the total mols of gas at equilibrium?
  
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