law

  1. S

    The Story Behind Hess Law

    My book introduces Thermochemistry with the concept of heat and how a calorimeter works. After that, it explains the story behind Hess Law and says that one of the reasons it was created is because a calorimeter can't calculate fast chemical reactions, but it doesn't really say the problem with...
  2. C

    Rate Law Problem

    The reaction of tert-butyl bromide with azide ion in aqueous solution is proposed to proceed by the following mechanism: (CH3)3CBr(aq) ⇌ (CH3)3C+(aq) + Br–(aq) where k 1 is the forward reaction and k -1 is the reverse reaction (CH3)3C+(aq) + N3–(aq) -> (CH3)3CN3(aq) k2 is the rate constant...
  3. C

    Chemistry Olympiad Rate Law Problem

    The reaction of tert-butyl bromide with azide ion in aqueous solution is proposed to proceed by the following mechanism: (CH3)3CBr(aq) ⇌ (CH3)3C+(aq) + Br–(aq) where k 1 is the forward reaction and k -1 is the reverse reaction (CH3)3C+(aq) + N3–(aq) -> (CH3)3CN3(aq) k2 is the rate constant...
  4. G

    rate law and mechanism

    Rate Laws and Mechanisms? The reaction and rate law for the gas-phase decomposition of dinitrogen pentaoxide are* 2N2O5(g) → 4NO2(g) + O2(g)* rate = k[N2O5]* Which of the following are valid mechanisms for the reaction?* 1.* N2O5 ⇌ NO3(g) + NO2(g) [fast]* NO2(g) + N2O5(g) → 3NO2(g) + O(g)...
  5. S

    Enthalpy & Hess's Law

    Hello everyone, I need quite urgent help. I have carried out experimentally two reactions as follows: 1. CaO + H2O -> Ca(OH)2 2. Ca(OH)2 + 2HNO3 -> Ca(NO3)2 + 2H2O to prove Hess's Law for this reaction: 3. CaO + 2HNO3 -> Ca(NO3)2 + H2O How do I do calculate the enthalpies? Is q=mcΔT enough...
  6. S

    law of gasses

    A mixture of 7.50 g He and 24.5 g Ne has a pressure of 640. mm Hg. What is the partial pressure of each of the gases?
  7. S

    Pulse Oximetry Deriving S(oxygen saturation value) using beers law?

    Hey guys im having problems trying to derive this equation S(oxygen saturation value) = (E1r-BE2r)/(E1r-E1o+B(E2o-E2r)) using Beers Law I = Io x 10^-ecd . Any help would be greatly appreciated thanks!!
  8. S

    Pulse Oximetry Deriving S(oxygen saturation value) using beers law?

    Hey guys im having problems trying to derive this equation S(oxygen saturation value) = (E1r-BE2r)/(E1r-E1o+B(E2o-E2r)) using Beers Law I = Io x 10^-ecd . Any help would be greatly appreciated thanks!!
  9. S

    dALTON LAW

    mixture of gases contains 16g oxygen , 14 g of nitrogen and 22g carbon dioxide. the mixture is collected above water at a temperature 25 Celsius. the total pressure is 1 atm and vapor pressure is 40 torr at 25 Celsius. what is the partial pressure of carbon dioxide? my work : mole of oxygen =...
  10. D

    Beer's Law

    Hello, When using Beer's Law calculation (A = ƐLc) when the absorbance (A), path length (L) and specific absorbance are know, do I need to convert the specific absorbance to molar absorbance. Example: If the specific absorbance is 253, is the molar absorbance 2530? Thanks.
  11. M

    Hard gas law problem

    Hello can someone please solve this problem for me step by step and show as much work and calculation and reasoning as possible. Assume that you are trying to show how the problem can be solved to another student who does not understand what you are doing. Thank you. 1. Trimethyl aluminum...
  12. D

    Boyle's law lab problem

    Two books are sitting on the syringe. The mass of the first book is 4.263 kg adn the mass of the second book is 6.36 kg. If the pressure of the room is 1.34 atm, what is the pressure that Book 1 exerts on the syringe? I have no idea how to do this. I am looking for help, not the answer. This...
  13. S

    Beer Lambert Law Question. Please help!

    Hey This is my first post. Hope you can help! Im quite confused as to how to go about this. Will appreciate any help! Calculate the percentage of stated content of acetylsalicylic acid in aspirin tablets using the following information: 20 aspirin tablets, weighing 1.95 g, are ground and 0.21...
  14. M

    Yet Another moles/gas law question :( Please Help me :D

    Hi all, sorry to ask another question but this is for an assignment and I can't leave them blank :( A small amount of zinc granules were reacted with an excess of dilute HCL according to the following equation: Zn(s) + 2HCl(aq) --> ZnCl2(aq) + H2(g) The hydrogen gas produced was collected...
  15. M

    Chemistry Moles and Gas Law Question? Please Help?

    Hi! So the question is: Hydrochloric acid of concentration 2.0 mol dm^-3 is used to descale a kettle containing 25 grams of scale (calcium carbonate) (i) what volume of water containing 0.002 ml dm^-3 calcium hydrogen carbonate Ca(HCO3)2 would need to be boiled to produce this amount of...
  16. S

    Beer's Law question

    The Beer's Law slope for the Fe-phenanthroline complex is found to be .2100 L/mg Fe. The absorbance of the diluted unknown solution prepared is found to be .440 What is the concentration of the original unknown solution? A= ebc A=slope*conc .440=.2100L/mg*conc conc= 2.09 mg/L Correct?
  17. S

    Hess' Law problem

    Given : ClO(g) + O3(g) ---> Cl(g) + 2 O2(g) delta H of rxn= -29.90kJ 2 O3(g) ----> 3 O2(g) delta H of rxn= 24.18kJ Determine the value of heat of reaction for the following: Cl(g) + O3(g) ----> ClO(g)+O2(g) Delta H = ? ============================================================...
  18. S

    Beer-Lambert Law

    Do the following calculations using a stock standard Alphazurine solution of 1.454 x 10–4 M. 1. A 10.00 mL sample of this solution is diluted to 100.0 mL in a volumetric flask. Determine the concentration of the working standard. 2. Calculate the concentration of a dilution made by mixing...
  19. B

    Hess's Law

    Can somebody please explain how to do the following two questions, please? 1.For the reaction 4Fe(s) + 3O2(g) --> 2Fe2O3(s) how much heat would be liberated by the combustion of 5.00 g of iron metal in excess oxygen? 2. If 3.00 g iron metal are reacted in a calorimeter with a heat capacity of...
  20. L

    additivity of Beers law

    Hi guys, No idea where to even start on this problem, any help appreciated. Thanks. Analytes X and Y are both NIR absorbing species, and their concentrations in mixtures can be determined by NIR spectrometry. The absorption data for the two pure species in a non-absorbing...