Answers created by Truong-Son N.

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• What is the Cartesian form of #( -2 , (13pi)/6 ) #?
  
• What is another way to say density?
  
• How do you verify the identity #sqrt((1-costheta)/(1+costheta))=(1-costheta)/abssintheta#?
  
• What is the integral of #sqrt(x^2 + 1)#?
  
• A student announced that she had made a sample of a new material that had a density of 0.85 g/#cm^3#. Can you tell how large a sample she had made? How?
  
• How do you find two unit vectors that are orthogonal to (-3,4)?
  
• How many electron orbitals exist?
  
• According to the molecular orbital theory, what is the bond order in #B_2^+#?
  
• Is there a formula for kinetic theory of gases (the collision with a wall)? If there is, how can I derive it?
  
• How do I make a phase diagram for water?
  
• Is entropy a state function? How? Prove it?
  
• What is an example first order half life problem?
  
• What is the enthalpy of hydrogenation of propene?
  
• Question #a9af4
  
• For the reaction #"PCl"_3(g) + "Cl"_2(g) -> "PCl"_5(g)#, the percent yield was #88.2%# for a certain experiment. If #"77.4 g"# of #"PCl"_3# was consumed in the presence of xs #"Cl"_2(g)#, what would be the actual yield of #"PCl"_5(g)# for this experiment?
  
• Which of these designates a gas at room temperature?
  
• How would I convert kinetic energy for one particle in six dimensions (x, y, z, and their time derivatives) from Cartesian to spherical coordinates? Note: #dotq = (delq)/(delt)#, and this is from a 1962 Statistical Mechanics textbook by Norman Davidson.
  
• How is molarity related to concentration?
  
• Question #7a6ca
  
• How do you integrate #int (x+4) / (x^2-x-2) dx# using partial fractions?
  
• What is the difference between #"NI"# and #"Ni"#? How many elements are in each?
  
• At what Celsius temperature does mercury change from a solid to a liquid?
  
• At what Celsius temperature does lead change from a solid to a liquid?
  
• Is #f(x)=(x^3+3x^2-4x-9)/(x+1)# increasing or decreasing at #x=0#?
  
• A particle moves according to the equation #s=1-1/t^2#, how do you find its acceleration?
  
• How do you find the derivative of #sqrt(3x+1)#?
  
• At which Celsius temperature does lead change from a solid to a liquid?
  
• The lattice energy for sodium iodide is 700 kJ/mol, while that for calcium sulfide is 2775 kJ/mol. Which of these salts do you predict has the higher melting point?
  
• What is the mol fraction of ethylene glycol in the solution phase for an aqueous solution with a vapor pressure of #"760 torr"# if the pure vapor pressure was #"1077 torr"#?
  
• How do you graph #y=4x+3# using a table?
  
• Question #d5082
  
• What is the mass of an electron?
  
• What is the standard enthalpy of atomization?
  
• Why are aromatic compounds stable?
  
• Is disodium gas a metal?
  
• What mass of water and urea were mixed, if the mol fraction of urea is #0.0825# and #"60 g"# of solution is present?
  
• What is the difference between the first and second ionization energy of an element?
  
• Which atomic orbitals of which subshells have a dumbbell shape?
  
• How do you integrate #(x^(1/3))/(((x^(1/3))-1))#?
  
• Question #fb528
  
• What is a compound that has two halogen atom on adjacent carbon atoms is called?
  
• Identify the missing species and the radioactive decay process?
  
• How do you use Newton's method to find the approximate solution to the equation #x+1/sqrtx=3#?
  
• What are values of ΔH, ΔU, ΔS for 1 mole of H20?
  
• How do you find the Maclaurin Series for #(sinx cosx) / x#?
  
• What is the formula of 4-methylbutanoic acid?
  
• Under what conditions is the freezing of water spontaneous? Why?
  
• Which Rydberg constant should be used for hydrogen atom? #"109737.32 cm"^(-1)# or #"109678.77 cm"^(-1)#?
  
• Question #29cee
  
• How do you find the nth term of the sequence #1, 1 1/2, 1 3/4, 1 7/8, ...#?
  
• For what values of x is #f(x)= 2x^3-9x # concave or convex?
  
• What is the difference between ideal and nonideal binary solutions? What are examples?
  
• Sir i need help for understanding symmetry elements which is the basis of group theory.i have read many books containing this subject , however i can't imagine these elements.please help me.thanking you?
  
• Find Van der Waals constants and what is the pressure for C2H6?
  
• Chemical reaction is most often occurring with the constant parameter of ______?
  
• What is the difference between the Rydberg constants #R_H = "109678.77 cm"^(-1)# and #R_(H) = 2.18 xx 10^(-18) "J"#?
  
• Which of these molecules is polar? #"SiF"_4#, #"XeF"_4#, #"BF"_3#, #"SF"_4#
  
• What is the difference between the Rydberg constants #R_H = "109678.77 cm"^(-1)# and #R_(oo) = "109737.32 cm"^(-1)#?
  
• Is the heat of fusion endothermic?
  
• The value of #DeltaH_(vap)# of substance X is 45.7 kJ/mol and its normal boiling point is 72.5 degrees C. How do you calculate #DeltaS_(vap)#, #DeltaS_(surr)# and #DeltaG_(vap)# for the vaporization of one mole of this substance at 72.5°C and 1 atm?
  
• How concentrated is concentrated acid? What about dilute acid?
  
• What is the rate constant for dimethyl ether after a couple of hours?
  
• If #"85 mL"# of #"0.900 M"# #"HCl"# is combined with #"85 mL"# of #"0.900 M"# #"KOH"# in a coffee-cup calorimeter, and the heat capacity of the calorimeter is #"0.325 kJ/"^@ "C"#, what is the final temperature if the initial temperature was #18.24^@ "C"#?
  
• Under what conditions is the melting of ice spontaneous? Why?
  
• How would the reaction of a metal oxide with hydrogen gas occur?
  
• How does light bend if it is going from an object with a higher density through an object with a lower density?
  
• How do you find #lim (1/t+1/sqrtt)(sqrt(t+1)-1)# as #t->0^+# using l'Hospital's Rule?
  
• At #25^@ "C"#, for the reaction #"N"_2"O"_4(g) rightleftharpoons 2"NO"_2(g)#, the equilibrium constant is #K_c = 5.85xx10^(-3)#. #"20.0 g"# of #"N"_2"O"_4# were added to a #"5.00-L"# container. What is the molar concentration of #"NO"_2# at equilibrium?
  
• Is a reaction that is exothermic and becomes more positionally random spontaneous or non spontaneous? What about less positionally random? Is there enough information to tell?
  
• Is a reaction that is endothermic and becomes less positionally random spontaneous or non spontaneous? What about more positionally random? Is there enough information to tell?
  
• Why can't we use sodium chloride solution to get the sodium metal?
  
• What does the word mixture mean to a scientist?
  
• What is the new vapor pressure for water that now boils at #90^@ "C"# instead of #100^@ "C"#?
  
• What is the new boiling temperature for bromine, if the pressure changes from atmospheric pressure to #"76000 Pa"#?
  
• What is the volume after 5 hours in this first order reaction?
  
• Question #29d0f
  
• Explain the mechanism of the Michael reaction?
  
• Is the ionic strength of a solution simply the sum of the concentrations of the reactant and product ions?
  
• Is hydroxide #""^(-)"OH"# or #"HO"^(-)#?
  
• Determine #f#, #c# and #p# in these reactions (Gibbs' Phase Rule)?
  
• Question #93e79
  
• What is the number of half-filled orbitals in an atom of chromium?
  
• What is the speed of the molecules dependent upon in a substance?
  
• Explain the basic properties of electrical charge?
  
• Explain why #"Li"_2"CO"_3# decomposes at a lower temperature, whereas #"Na"_2"CO"_3# decomposes at a higher temperature?
  
• How do I calculate the force constant, zero-point energy, and the energy level spacings for #""^(12) "C"""^(16)"O"# if #tildeomega_e = "2170 cm"^-1#?
  
• #[Ar]4s^2 3d^10 4p^4# is the noble gas configuration of which element?
  
• What is the standard state of methanol?
  
• Which of these is not an isomer of (the straight-chained) #"C"_6"H"_14# (hexane)?
  
• How do I determine the valency of a main group element?
  
• A solution is made by mixing 500mL of .3M benzoic acid and 400mL of .25M benzoate. What will the pH of the solution be?. Specifically, how do I find the concentration of the acid and base to use in the equation #pH=pKa +log( ([A^(-)])/([HA]))# ?
  
• A rigid sealed #"3.70 L"# vessel contains #"0.12 mol"# of #He(g)# and #"0.24 mol"# #Ne(g)# at #25^@ "C"#. What is the total pressure in the vessel?
  
• Why is the phase diagram of water so odd?
  
• Why is methane nonpolar? Explain in terms of polarity within a bond, and overall polarity based on symmetry.
  
• Is there an easy way to remember the order of filling of orbitals without diagram?
  
• How do you rank metallic character?
  
• What is the name of the bond that joins amino acids?
  
• How do you integrate #(1-(tanx)^2)/(secx)^2#?
  
• How do you find the sum of the series #\sum _ { k = 1} ^ { 4} ( - 1) ^ { k } ( k ^ { 2} + 1)#?
  
• Suppose that #f'(x) = 2x# for all #x#. What is #f(2)# if #f(1)=0#? What if #f(-2) = 3#?
  
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