concentration

  1. N

    How do I calculate the concentration of a stock solution?

    How do I calculate the concentration of a stock solution prepared in a 100cm3 volumetric flask that contains 75mg of Acesulfame K, 50mg of Saccharin and 200mg of Aspartame ?
  2. M

    Back Titration (or Indirect titration) to determine concentration of acetylsalicylic

    MW21 New Members 0 1 post Report post Posted 1 hour ago For school, we performed a back titration involving one brand of aspirin and were told to determine the quantity of acetylsalicylic acid in a single tablet. sodium hydroxide was added in excess then the solution was heated. the excess...
  3. 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...
  4. M

    Measure NA chlorate concentration vs chloride

    Hello, I am using an electrolytic cell to convert sodium chloride to sodium chlorate (NOT per-chlorate, just straight NaCLO3). How can i measure the relative concentration of chlorate to chloride? I need to find a way to track how much of the conversion has been completed. The application is...
  5. F

    Formula for pH adjustment

    I have come up with the following formula but the results do not seem right. Can someone confirm this is right or wrong. If wrong suggestions would be appreciated. Problem: I need to adjust the pH of large quantities of waste water pH as high as 12 with a 35% Sulfuric Acid solution (...
  6. P

    Solubility and concentration

    Hi :) I am confused on what formulas to use when answering questions like these: 1. A sample of pond water contained 88.00 µg g−1 of dissolved oxygen gas. Calculate the amount in grams of dissolved oxygen in 4.00 L of pond water. 2. A desirable level of dissolved oxygen in river water is 8...
  7. X

    Finding Riboflavin Concentration in Tablet

    I need help understanding how to solve for the riboflavin concentration in a tablet. Here's the problem: The ribofalvin concentration in an unknown powder solution is 50.4 ppm. The total volume of the unknown powder solution is 250.00 mL. What is the concentration in the tablet (mg...
  8. A

    Freezing point depression of ZnCl2

    Hello, I did an experiment on how different concentrations of ZnCl2 affect the freezing point of demi water. My results were that till a concentration of about 10 mol dm-3 the freezing point decreased (more or less in a linear manner). After that at concentrations of 15mol dm-3 the freezing...
  9. C

    Maintaining fluoride ion concentration

    This is the problem: Fluoridation is done by continuously adding sodium fluoride to water drawn from a reservoir. Assume you are responsible for the fluoridation of your city's water. How many tons of sodium fluoride must you add to the water supply each year (365 days) to maintain a fluoride...
  10. D

    Cumulative Concentration

    I need to figure out the cumulative concentration of specific metals in both mg/L and mg/kg that have been added to a known volume of fluid through the addition of certain products. For example product X would have 13.2mg/kg of nickel and 5 units of product X have been added to 100m3 of fluid...
  11. K

    FeEDTA Concentration

    For gold dissolution in Sodium Thiosulfate solution, I have to add FeEDTA at a concentration of 0.002 mole/L. I have with me Ferric sulfate and EDTA (Ethylenediaminetetraacetic acid) separately. Please advise me how many grams of ferric sulfate and EDTA I have to dissolve into the solution...
  12. K

    Sodium Thiosulfate Concentration

    Kindly explain the following: I have to prepare 1 liter solution of sodiumthiosulfate at a concentration of 0.3 M/L How many grams of sodiumthiosulfate shall I add to one liter of water. Please explain the calculation method also. Thanks!
  13. U

    Calculate the concentration?

    The rate constant for the reaction 2N2O5(g) → 4NO2(g) + O2(g) is equal to 4.37 x 10–5 s–1 at 30 ºC. If the initial concentration of N2O5 is 0.372 M what concentration of NO2 will be observed after 145 minutes? Assume that initially no NO2 was present in the reaction vessel. Thanks in advance
  14. Z

    Molar concentration

    How many litres of (NH3) (the volume is measured in standart conditions) must be dissolved in 200 g of a 10% solution NH4OH to obtain 15% solution of the ammonium hydroxide?
  15. S

    Molarity and Ion concentration question

    I finally got to the last page of my assignment, and there is a problem I can't figure out how to do. It is this: Given the reaction below, if 52.2mL of 0.771M Ba(NO3)2 reacts with 65.9mL of 1.11M NaF, calculate the concentration of all ions in solution after the reaction. Ba(NO3)2 (aq) + 2NaF...
  16. A

    Calculate the label concentration of the NaOH solution

    I've been stuck on this question for hours now, I dont really know where to start and I was wondering if you guys could help me out The concentration of a solution of NaOH of unknown concentration was determined in the following titration: 25.00-mL aliquots of the NaOH solution, measured by...
  17. J

    Concentration

    Hello, I can't seem to get the right answer for this question: 300 cm3 of water is added to a solution of 200 cm3 of 0.5 mol dm–3 sodium chloride. What is the concentration of sodium chloride in the new solution? So far I have done: 300 cm3 = 0.3 dm3, 200cm3 = 0.2 dm33 C = n/v =0.5/(0.3+0.2)...
  18. B

    Serial dilutions help

    Hi there - please help! If I have 10mls of stock solution at 10-3 M (I assume this means 10-3 moles per litre). How do I create 1ml of 10-4M? and then 1ml 3x10-4M solutions? Do I just take 1 ml of stock solution and add this to 9 mls of distilled water for 10-4? And then take 3 mls of this and...
  19. L

    Some chemistry questions I need help with

    1. a)You put [H2] = 0,70M, [I2] = 0,70M and [HI] =1,50M. And the K value is 49. Decide the equilibrium concentrations. H2 + I2 <-> 2HI b) Which concentration HI gets inserted if the iodine concentration at a new equilibrium is 0,42Molar. The K value is still 49. c) What happens with the...
  20. G

    Two hydroxides; which will precipitate

    Im struggling with this question: Im not looking for the answer, maybe just an example of how to do a similar question. Any help you can offer is much appreciated. Suppose two hydroxides, YOH and Z(OH)2, both have Ksp=1/0*10^-12 and that initially both Y+ and Z^2+ are present in a solution of...