determination

  1. J

    Determination of concentration of dissolved amides???

    Hey guys! I am completely stuck. Are there any laboratory methods for determining the concentration of trace dissolved amides in water? The range would be 0-2 mg/L of a mixture of long-chain secondary amides. Preferably any spectrophotometer methods not involving expensive equipment such as MS...
  2. A

    determination of Na2CO3 and NaOH in Zn/Ni elecrtolyte

    Hi all, my name is Ana and I am new hear. I work at chemical lab and I have a problem with determination amound of Na2CO3 in presens of NaOH in Zn/Ni electrolyte. Could you help me? The method who we use is: 1./ 5 ml of sample is add in 250 ml conical flack. Then we put 100 ml H20 and...
  3. N

    Determination of flavonoids in hawthorne

    Hello, I have 2 questions from an experiment's procedure: First, When preparing a crude extract from Hawthorne for determining its flavonoids, why do we add 1cc methenamine 0.5% to the solvent (20cc acetone and 2cc hcl 25%) before reflux? Second, what happens when we add AlCl3 to the extract...
  4. W

    Ethanol % in vapor determination

    I have a temperature probe in a stream of vapor coming off a boiling ethanol solution, and a barometer monitoring ambient pressure. I need to convert the vapor temperature (boiling point) into the % ethanol in the vapor with correction for ambient pressure. My objective is to have a single...
  5. D

    Moisture determination using Karl Fischer Method

    Hi guys, I hope you can assist me. Our laboratory recently acquired a new Titration unit to determine moisture content in oil. The unit is working excellently, but what I want to find out if a sample is tested today in the morning and the same sample is tested at night there will be a...
  6. J

    Determination of Vitamin C content in a vegetable

    Hi, I'm just starting my course work for A2 chemistry. It's based on finding the Vitamin C content of a pepper using a titration. I've done a bit of research and I know that I will be using Iodine to react with the ascorbic acid (Vitamin C), using a starch indicator. However the method I found...
  7. 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...
  8. H

    Spectrophotometry - determination of arginine

    Hi everyone! I'm making a research and I want to figure out how much L-arginine is in a capsule, which is said to contain 0,5 grams of L-arginine. Basically I want to check if the nutrition values on the lebel of the product are right. I decided to try with spectrophotometric determination...
  9. F

    Empirical & Molecular Forumlae Determination Woes

    The aim of the practical experiment we are undertaking is to determine which copper oxide (I or II) our sample is by measuring 'stuff' and thereby calculating its empirical formula. A specific question asks: "Why can't the molecular formula of your oxide be calculated from the information you...
  10. W

    Determination of Equilibrium Constant for Ferric Thiocyanate

    Hi everyone! I'm having trouble with this formal lab report.. and so I have taken the liberty to snap some pictures and also willing to upload and collaborate to share my work with anyone willing to help me on this. Unfortunately, my lab instructors weren't so clear in explaining everything...
  11. S

    Colorimetric Determination of Iron in Multivitamins

    What happens if you omit the hydroquinone from the the solution prepared to determine the amount of iron in the unknown. What effect is that omission likely to have on the results? I know hydroquinone is the limiting reagent and is oxidized. PS: I think because in the experiment, it donates...
  12. J

    Determination of Enthalpy Change Lab

    I already completed a lab using H3PO4 and NaOH to find the enthalpy change. I am now trying to do the post lab questions and do not understand some of them.... 1. Calculate the amount of heat energy. Use 1.11 g/mL for the density. Use 4.18 J/(g degrees celcius) as the specific heat. I got an...
  13. J

    HMO pi orbital determination

    Almost finish with my problem set but then I came across this problem... What is the total number of HMO pi molecular orbitals (bonding and antibonding) in 3-methyl-5-(1-ethenyl)-1,3,5,7,9-decapentaene? Please explain how you arrived at your answer. So far I only managed to draw out the...
  14. T

    Help with spectrophotometric determination of equilibrium constant?

    So we had this experiment, we used Fe3+ and SCN- to produce [Fe(SCN)]2+, and I know how to get the best fitting line for the calibration, but how do I get the equilibrium concentrations of the products and the reactants when determining Keq's of unknown solutions? Also, can H2O be used as a...
  15. S

    Theoretical mass determination help

    What is the theoretical mass of magnesium necessary to form 1 gram of hydrogen based on the following balanced formula: 2HCL+ 4 mg ---> 2mg(subscipt 2)CL + H(subscipt 2) Please show work. I keep getting 48.6 grams?