Answers created by Truong-Son N.

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• What are concentration cells? Give examples.
  
• What does photoelectron spectroscopy do?
  
• How does your experimental value (0.00538 moles) compare to the actual molar mass of magnesium? Please provide a clear explanation.
  
• Thermodynamics question homework help?
  
• Are reduction reactions always endothermic?
  
• Place a rectangular book with a length L in parallel with the end line of the desk and push it a little by little. How long can a book go out of the desk without falling off? (use the statics and equilibrium concepts to explain this)
  
• Light of wavelength 5000 Å and intensity 39.8 W/m² is incident on a metal surface. If only 1% photons of incident light emit photo electrons, then what will be the number of electrons emitted/sec/unit area from the surface?
  
• If the concentration of #NH_3# (from reaction below) is changing at a rate of #0.25# M/sec, what is the rate of change of #H_2# (in M/sec)?
  
• What is Kp? What goes on in a Kp equation?
  
• Which orbitals has the electron with the greatest penetrating ability?
  
• The limiting line in balmer series will have frequency of ?
  
• #"H"_3"C"-"C"="CH" + "HBr" -> #?
  
• How do you integrate #f(x)=(x^2+1)/((x^2+6)(x-4)(x-9))# using partial fractions?
  
• Do you read ph levels on the ph paper when it is wet or dry?
  
• Knowing #T-T_s=(T_0 - T_s)e^(kt)#, A pan of warm water (46dgC) was put in a refrigerator. 10 minutes later, the water's temperature was 39dgC; 10 minutes after that, it was 33dgC. Use Newton's law of cooling to estimate how cold the refrigerator was?
  
• If a spring is cut into 9 equal pieces then they r connected in series with the same mass.what will be it's frequency relative to the original frequency?my text book says that the answer is 9f.but Time period of spring does not depend on length.right?
  
• List the similarities and differences between ionic, covalent, and metallic bonds?
  
• What is the reaction between ammonia and bleach that makes it unsafe to mix the two?
  
• What is the x- intercept and y- intercept of #y= -4(x+2)#?
  
• Value of log(0.02)/(0.07)?
  
• Is #NH_3# a gas or a solid? How do you know?
  
• Use the de Broglie's Wave Equation to find the wavelength of an electron moving at 3 × 106 m/s. Please show your work. Note: h = Plank's constant (6.62607 x 10-34 J s) ?
  
• A two dimensional square box with a corner length L, the energy level of a particle with a mass #h^2/(8mL^2)(n_1^2+n_2^2)# . What is the quantum number of the first, second and third degenerate energy levels?
  
• If you are forming a snowball with your bare hands, what is the direction of heat flow?
  
• Two different gases, at STP, have the same number of particles. What can you say about the respective volumes of the two gases?
  
• Why is the spectrum of helium different from that of hydrogen?
  
• When hydrogen atom excites from ground state what happens to its kinetic and potential energies?
  
• Why is using a graduated cylinder more accurate than using a beaker?
  
• How do I convert mole fraction to molality? Then also to percent by mass?
  
• Thermochemical equations practice problems video: a delta T value is given of -890.4kj. How did you get that value? I thought we had to work that out... confused and a bit panicky. Assignment due Friday and exams next week. Thank you so much
  
• When a nucleus undergoes gamma decay, what happens to its atomic number?
  
• Why are the convergence lines in the UV spectrum used to calculate the ionization energy of hydrogen rather than the convergence line in the visible spectrum?
  
• How do I find Ka? 2.303pKa=-logKa
  
• The mass of an atom may be determined by adding the masses of the protons and neutrons in the nucleus and then subtracting the mass defect. Why is it unnecessary to include the electrons when determining the mass of an atom?
  
• FRQ - Gases?
  
• How do you find electron configurations for ions?
  
• Why does brom o- 1 butene and bromo 2 butene undergo resonance?
  
• Calculate the wave number of photon whose energy is 6.626×10^-20 J?
  
• Actual yield is always less than theoretical yield?. Give two reasons
  
• Why is van der Waals equation used?
  
• Benzene, a solvent, has a freezing point of 5.5°C and a F of 5.12° CM. If 45.6 g of CCl4 are dissolved in 520.0 g of benzene, what will the freezing point of the solution be?
  
• How many orbitals make up the 4d subshell?
  
• Raoult's Law and vapor pressure?
  
• How to calculate the max pH at which reaction occurs using the Nernst equation?
  
• How many oxygen atoms are contained in 223.4 grams of lithium carbonate and how do I get this answer?
  
• If 0.2 mole NaCl is added to 2 mole water then vapour pressure of the solution is(vapour pressure of pure water is 760 torr)?
  
• Is it true that the value of k depends on the amount of reactants and products mixed together initially?
  
• Why does NH3 have a larger bond angle than PH3?
  
• What is the arc length of #f(x)= e^(3x)/x+x^2e^x # on #x in [1,2] #?
  
• How much heat must be removed to freeze a tray of ice cubes at 0 C if the water has a mass of 225 g?
  
• How do I solve these?
  
• What is the electron configuration of an element with atomic number 8?
  
• How do I solve this problem? "if concentrated acetic acid is 12M, then what is the molarity of 100 mL of vinegar (5% solution)? show work."
  
• What is the molarity of HCl found in a titration where 30 ml of HCl is titrated with 15 ml of .1M NaOH?
  
• The energy per mole of photon of electromagnetic radiation of wavelength 4000A° is ?
  
• If the ionization potential for hydrogen atom is 13.6eV, then the wavelength of light required for the ionization if hydrogen atom would be ?
  
• If you have 435.0 g of water and wish to make a 7.68 M solution of NAOH how many grams of the solute would you have to add to the water that you have?
  
• How many ML of 5.6 M solution of NaCl will be necessary to make 250.0 g of AlCl3?
  
• Why is CO a Lewis base?
  
• How many microstates are possible for a molecule?
  
• Why is that phenothalein have no effect on litmus paper despite the fact that it is basic in nature?
  
• Is covalent bonding between "s" orbitals directional or non-directional? Why?
  
• Which are the orbitals(s,p,d,f) have center of symmetry?
  
• What are the irrational numbers of the following groups?Why? 1. n=2, l=3, m =0 ； 2. n=2, l=2, m=1 ；
  
• What is an equation that you can use to find the number of Calories in any number of grams of trail mix?
  
• What are the seven fundamental units?
  
• Two people meet in the purple room on the fourth floor of a building. On departure, one person travels West 16 feet, South 9 feet, and Down 9 feet. The other person travels North 16 feet, East 8 feet, and Up 9 feet. How far apart are the two people? Round
  
• If a Eudiometer collects H2 from a reaction with Mg, under the conditions listed below, what's wrong with these calculations?
  
• If reaction between acid and metal always give salt and H2????
  
• Why when the shape of molecules become more compact it's boiling point decrease while when intermolecular force become strong boiling point increase?
  
• A light source of wavelength λ illuminates a metal and ejects photo-electrons with (K.E)max=1eV. Another light source of wavelength λ/3 ejects photo-electrons from the same metal with (K.E)max=4eV. Find the value of Work Function?
  
• What does amplitude measure?
  
• Using Henderson-Hasselbalch equation, calculate the volume of 0.20 M Acetic Acid and 0.2 M Sodium Acetate needed to prepare 50 mL of 0.1 M Acetate Buffer solution (pH = 4.5). pKa of Acetic Acid is 4.74?
  
• Van't hoff factor of Hg2Cl2 in its Aqueous solution will be (it is 80% ionised in the solution) ? (1) 1.6 (2)2.6 (3)3.6 (4) 4.6
  
• NH4HS=NH3+H2S the equilibrium pressure at 25 degree Celsius is 0.8 atmosphere then kp for the reaction is ?
  
• Fill in the blanks about blackbody radiation?
  
• What is its average relative atomic mass?
  
• The arrow in the middle of a chemical equation means this....?
  
• What happens when matter and antimatter collide?
  
• Where is visible light located on the electromagnetic spectrum?
  
• Which has the highest lattice energy?
  
• How does 2s orbital differ from 1s?
  
• In a 10-liter capacity container the following system is in equilibrium at 25 celcius degrees: NH4HS (s) <-> NH3 (g) + H2S (g) K = 1.8 x 10 ^ -4 ?
  
• What is the pH of a 0.026 M Sr(OH)2 solution?
  
• What are scientific models?
  
• The half-life of a certain first-order reaction is 15 minutes. What fraction of the original reactant concentration will remain after 2.0 hours?
  
• A certain first order reaction has a rate constant at .0001 at 30 degrees Celsius and an activation energy of 120 kJ/mol. What is the rate constant for this reaction at 64 degrees celsius?
  
• The #K_p# of H2+I2<->2HI is 50.2 at 445°C. #DeltaH_(rxn)^@# for this is 25.84 kj/mol. How can I find the entropy of this reaction?
  
• Does atmospheric pressure affect the vapor pressure of a liquid?
  
• Why do rates of reaction change with pH?
  
• What is the rate constant for this first-order decomposition at 325°C? If the initial pressure of iodoethane is 894 torr at 245°C, what is the pressure of iodoethane after three half-lives?
  
• Hydrogen gas (#"H"_2#) is stored in a tank of volume #"2000 L"# at a temperature of #"653 K"# and #"3 barg"#. Calculate the thermal energy transferred from cooling the hydrogen gas in the tank to #220^@ "C"#?
  
• What is the molar entropy of a system with 150000 microstates at a certain temperature?
  
• The Ksp for AgI is 8.5 x 10-17. The Ksp for TlI (thallium iodide) is 5.5 x 10-8. A one litre solution contains 0.035 mol L-1 Ag+ ion and Tl+ ion. When TlI begins to precipitate, what percentage of Ag+ remains in the solution?
  
• The Ksp for AgI is 8.5 x 10-17. The Ksp for TlI (thallium iodide) is 5.5 x 10-8. A one litre solution contains 0.035 mol L-1 Ag+ ion and Tl+ ion. When TlI begins to precipitate, what can be said about the extent of precipitation of AgI?
  
• What is an example of buffering capacity?
  
• How do you calculate microstates in chemistry?
  
• A solution is made containing 4.92 g of sodium lithium chloride per 347 g of water. what is the #%"w/w"# or percent by mass of the solute?
  
• Help with entropy/reaction rates homework?
  
• What other thermodynamic properties besides temperature and pressure may be graphed in phase diagrams?
  
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