answers

watching

views

11 Dec 2019

Show your calculations for producing 10 mls of the following standards (in ppb) using the 500 ppm Pb2+ stock solution: 200, 100, 50, 10, 5, and 1 ppb. Be sure to carry out a serial dilution from the 500 ppm stock solution to achieve these concentrations. Dilutions should be no greater than ten-fold. Assume 10, 20, 25, 50, 100mLvolumetric flasks, 1,2,3?,4,5,6,7,8,9,10,15,20,25 volumetric pipets and 50mLburettes are available for use.

answers

watching

196

views

For unlimited access to Homework Help, a Homework+ subscription is required.

Join us on Discord

Chemistry Study Group

Join now

Related questions

1. Assuming the tonic water used in an experiment contains 50 ppm quinine, what will be the final diluted concentration after following the dilution here:

-Pipet 5.00 mL of Tonic Water into a 250 mL Volumetric flask. Dilute to the mark with 0.05MH2SO4 and mix thoroughly.

-Pipet 5.00 mL of the above solution into a 25 mL Volumetric flask. Dilute to the mark with 0.05M H2SO4 and mix thoroughly.

2. Based on the answer to number one, determine a good range of quinine concentrations to analyze, and develop a plan for dilution to create 5-6 standards within that range.

A few things to keep in mind: you will be given a 1 L stock solution of 100.0 ppm quinine in 0.05 M H2SO4 as well as a separate 1 L of 0.05 M H2SO4. All standards will be made using these two components. You will use 100 mL volumetric flasks, and can use 1, 5, 10 and 20 mL volumetric pipettes.

Part A observations

Concentration of NaOH = 9.433 â¢ 10^-6

Part B observations

Part A

-How do I determine the 'E' for my dye

Part B

-Determine the order of the reaction with respect to Erythrosim B and NaOCl

-Determine Kobs for each trial

-Determine Ktrue for the reaction

Prepare Mg standards: Dilute 100-ppm Mg standard stock solution (you made previously) to the following concentrations in the previously cleaned test tubes. Use volumetric pipets to transfer the liquids. Again this is your standard solutions whose concentration accuracy is critical to your results. Treat the pipet used to transfer the standard solution with all the proper cleaning/coating steps. Read the markings on the pipet carefully during transfers.

[Mg] made Volume of 100-ppm Mg Volume of d.i. water

(use 5-mL grd. Pipet) (use 10-mL grd. Pipet)

50 ppm 5.00 mL 5.00 mL

25 ppm 2.50 mL 7.50 mL

12.5 ppm 1.25 mL 8.75 mL

Mix the solution in each test tube well by capping and inverting the text tubes.

At this point, place another seven (7) clean test tubes in a test tube rack. Label them 1 to 7.

2. In test tube 1 pipet 0.5-mL d.i. water. In Test Tubes 2-4 pipet 0.50-mL of three Mg standards you just made, one solution to one test tube. In Test Tubes 5-7 pipet 0.5-mL of the bovine serum sample.

3. Add 2.5-mL of TCA to each test tube prepared in Step 2, cap and mix well, and let stand for 5 minutes.

4. Centrifuge all 7 test tubes for 5 minutes. Make sure that you place the test tubes in the centrifuge in a symmetrical pattern so that the spinning will not be off balance. The test tubes will break if off-balance spinning occurs.

5. Use a pipet to transfer 2.00-mL of each solution or the supernatant solution from Step 4 into another set of 7 clean test tubes. To each transferred solution, add 2.00-mL of the TY working solution you made today and 1.00-mL (with a pipet) of 2.5M NaOH solution. Cap, mix well, and let stand for 5 minutes.

6. Bring these seven solutions to a Spectronics 20D spectrophotometer. Set the monochromator to 540nm. Zero the Transmittance with nothing in the cuvet chamber and then zero the Absorbance with water in the cuvet chamber. Measure the absorbance of each of the seven solutions, standards first from the least concentrated to the most concentrated, and then the serum samples.

Based on the procedures delineated in Steps (1)-(6), draw a "flow chart" to follow the path of your analyte Mg. Establish proportional relationships between (1) ppm Mg in serum calculated from the calibration curve with that in the original serum sample; (2) ppm Mg from the calibration curve with that in the curvet. (E.g., if you calculated 10-ppm Mg off the graph, what is it in the serum sample? In the cuvet?)

Weekly leaderboard

Home

Homework Help 3,900,000

Chemistry 830,000

Related textbook solutions

Basic Chemistry

Principles of Chemistry Molecular Approach

Principles of Chemistry Molecular Approach

Chemistry: Structure and Properties

Chemistry: A Molecular Approach

Chemistry: A Molecular Approach

Principles of Chemistry: A Molecular Approach

Chemistry: The Central Science

Related questions

Weekly leaderboard