1. J

    Acid-base calculation help

    -a pipette is used to remove 10cm3 portions of solution z - each portion is titrated with 0.0050moldm3 sodium hydroxide - mean Titre is 21.10cm3 Calculate number of moles of sulfuric acid in the 40cm3 if solution Z 2NaOH+H2So4=Na2SO4+2H2O Answer: moles of naoh=(21.10/1000)*0.00500=1.06*10^4...
  2. I

    How to convert from mol% to wt%?

    so the concentration of molecule A is 0.5% mol. The rest of the molecules are water. This is calculated by (number of molecules of A / total number of molecules) x 100 More specifically, this is [20 / (20 + 3980)] x 100 We are given that the molecular weight of A is 136 g/mol. I have no idea...
  3. Y

    HELP! Buffer calculation

    The question: You will prepare 2 buffer solutions, one which is pH 5.2 and one which is pH 8.8. Solutions available: 1M NH3, 1M NH4Cl, 1M ethanoic acid, 1M sodium ethanoate solution. Calculate how much of the above solutions you need to make 100cm3 of each buffer. Use the equation pH = pKa -...
  4. M

    Desperate help.reactor calculation exams question

    can some one help me here, This question is definately coming to my exams but do not understand it please. how you go the answer i would appreciate it please. please desperate help. An open straight-blade turbine of diameter 0.82 m is used to stir reaction mixtures in a 20 m3 batch with...
  5. S

    calculation of freezing point

    hi i am trying to figure out the way to calculate the freezing point of an aqueous solution which have 5 different components. if someone can refer me to an example or give me and example it will be great thanks in advance sharon
  6. T

    ABTS-TEAC calculation

    Hi, I'm a grad student and would appreciate your help with some calculations: I was using the TEAC protocol for antioxidants with ABTS. The numbers are as follows: Sample reading 0.35 Trolox reading 0.4 Blank reading 0.534 Trolox concentration 0.25 mM sample weight 0.3 gr final extraction...
  7. B

    will water evaporate?

    Hi everybody ! the question is will 100 mkL of water evaporate in 20 mL crimp top vial at 30% relative humidity, and normal conditions ? how to calculate it?
  8. P

    pH calculation with trisodium citrate and glycine

    I have troubles figuring out how to calculate pH value of solution with 15 mM trisodium citrate and 15 mM glycine. and how do I calculate the pH with addition of strong acid HCl in this solution? Thanks a lot.
  9. P

    pH calculation with trisodium acetate and glycine solution

    how do I calculate pH value of the solution with 15 mM trisodium citrate and 15 mM glycine? if HCl is added into this solution, how do I calculate pH in this solution? Thanks a lot.:)
  10. G

    conductivity offline determination via ionic strength

    Hi, I am looking for a way to adjust the conductivity in a bioreactor system by adding WFI. The problem is that a online measurement is not possible in this system, i.e. a certain amount of WFI has to be added to the system, then mixing occurs and then a sample is taken and the conductivity is...
  11. A

    Basic calculation?

    Ok, kind of at square one and need to be walked through this step-by-step. Thank you a ton in advance for any help you can provide! Calculate the amount (g) of each of the following salts that would need to be added to a 200 mL volumetric flask to produce a 2 M solution of S. A.) CaSO4 B.)...
  12. A

    g/mol Calculation

    Hi guys Please help me with the solution Hexadecane its Molecular weight/molar mass = 226.44 g/mol If I am adding 750 ul (Micro Litre) in 75ml water. How many g/mol have I added to the solution
  13. P

    Please Help With An Electrochemical Calculation.

    Hi, Please help me with this, I greatly appreciate any assitance; An electrochemical cell is given, one containing an 0.1M CuSO4 solution and the other one containing an 0.1M ZnSO4 solution. Then, the Cu ion concentration is decreased by adding an Ammonia solution NH4OH into the CuSO4...
  14. S

    HELP needed: Calculation the pKs1 for H2S in various ionic water according to Hearshe

    HELP needed: Calculating the pKs1 for H2S in various ionic waters I need the pKs for H2S in a water body containing Na,K,Mg,Ca,Cl,SO4,HCO3 with an ionic strenght of 1.5 and 28 C°. It should be possible to calculate this according to the paper of Hearshey and Millero (1988), The pK1* for...
  15. E

    Mole calculations confusion (please help!)

    Hello guys! Im really confused with this one part of calculating the number of moles in 1.00 gram the last part in bold is confusing me. why is the 2 negative? can someone please explain finding a number of moles in a certain number of grams? im really confused : ( this is what the teacher...
  16. D

    Molarity calculation

    What is the molarity of a solution made when water is added to 12g NaCl to make 100cm3(cube) of solution
  17. M

    stoichiometry calculation in organic chemistry

    Hello I need help on caculating this problem that I got stuck on, and couldn't find the exact answer for this, can someone help me solve this? Thank you. Propane will react with molecular bromine to make 2,2-dibromopropane and hydrogen bromide. In this reaction, 6.21 grams of propane react with...
  18. S

    Solution calculation question?

    You have a stock of 3M NaCl. You want to make a 1M solution. You should mix ___ ml of water with ___ ml of the stock to get the final concentration. Is this a C1V1=C2V2 type of problem? molar weight of NaCl is 58.4g/mol not sure if this affects the problem any? I appreciate any...
  19. H

    Buffer pH calculation

    I am stuck on this question.. Calculate the pH change for an acetate buffer consisting of 0.2M or sodium acetate and 0.2M of acetic acid following the addition of 5ml of 5M HCl. The pKa of the buffer is 4.75. I have calculated the original pH to be 4.75 but I am clueless as what to do next...
  20. V

    Calculation of Concentration

    I have an assignment to do and the only thing I need to know is how to calculate Concentration. I will do the rest myself. Here are the links with the experiment and my time results, please help me calculate the Concentration for each flask. I will answer the rest of the questions...