5.1g of toothpaste was weighed out and transferred to a 500 ml beaker. 250 ml of deionized water was added to the beaker by measuring cylinder, heated for 5 minutes on a hotplate, then sonicated for 10 minutes in an ultrasonic bath. The contents of the beaker was then transferred to a 1000 ml volumetric flask, made to the mark with deionized water and mixed thoroughly. Ten ml of this solution was removed from the volumetric flask (autopipette), 5 ml (measuring cylinder) of TISAB buffer was added. The concentration of the toothpaste obtained is 3.4mgF-/L, calculate the % of fluoride (F) in toothpast

5.1g of toothpaste was weighed out and transferred to a 500 ml beaker. 250 ml of deionized water was added to the beaker by measuring cylinder, heated for 5 minutes on a hotplate, then sonicated for 10 minutes in an ultrasonic bath. The contents of the beaker was then transferred to a 1000 ml volumetric flask, made to the mark with deionized water and mixed thoroughly. Ten ml of this solution was removed from the volumetric flask (autopipette), 5 ml (measuring cylinder) of TISAB buffer was added. The concentration of the toothpaste obtained is 3.4mgF-/L, calculate the % of fluoride (F) in toothpast

Appl Of Ms Excel In Analytical Chemistry

2nd Edition

ISBN:9781285686691

Author:Crouch

Publisher:Crouch

Chapter14: Chromatography

Section: Chapter Questions

Problem 9P

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5.1g of toothpaste was weighed out and transferred to a 500 ml beaker. 250 ml of deionized water was added to the beaker by measuring cylinder, heated for 5 minutes on a hotplate, then sonicated for 10 minutes in an ultrasonic bath. The contents of the beaker was then transferred to a 1000 ml volumetric flask, made to the mark with deionized water and mixed thoroughly. 10 ml of this solution was removed from the volumetric flask (autopipette), 5 ml (measuring cylinder) of TISAB buffer was added. From the calibration curve of potential difference (mV) vs log[F-] equation, y = -56.21x - 151.71, the mean of [F-] is 1.81E-04 and the concentration in mgF-/L is 3.4. The expected Fluoride in toothpaste according to toothpaste manufacturer: 1000 ppm Fluoride. So how do i calculate the % of F in the toothpaste sample?
To determine the soil distribution coefficient (Kd), 10 g of dry soil is spiked with 100 mg of ring-labeled 14C-atrazine, 10 mL of deionized water is added, and the system is shaken for 24 hours. The aqueous and solid phases are separated, and the solid phase is extracted with 50 mL of methylene chloride while the aqueous phase is extracted with three successive 5 mL portions of methylene chloride. The atrazine concentration in the 50 mL of soil extract is 10 mg/L, and the concentration in the combined 15 mL from the aqueous extractions is 0.4 mg/L. Based on this information, calculate Kd.
The concentration of purified OXA-M290 is tested with a BCA assay. Serial dilutions of a bovine serum albumin (BSA) stock solution are prepared, then pipetted into a 96-well plate; each dilution of the BSA standard is tested in triplicate. Then, bicinchoninic acid and Cu2+ ions are added to all of the wells of the plate. After incubating the plate for 1 hour, a microplate reader is used to measure the absorbance of all of the wells in the plate at 560 nm. This generates the following data: BSA conc. (μg/mL), Replicate 1 Absorbance, Replicate 2 Absorbance, Replicate 3 Absorbance 40, 1.360, 1.403, 1.481 20, 0.750, 0.745, 0.810 10, 0.380, 0.344, 0.398 5, 0.198, 0.160, 0.183 2.5, 0.090, 0.100, 0.085 1.25, 0.038, 0.043, 0.051 0.625, 0.024, 0.028, 0.019 Prepare a calibration curve using these data. You can use Excel, R, SPSS or an equivalent graphing software. In this graph, plot absorbance (y-axis) against the concentration of the protein standard (x-axis). Calculate and plot…
Oral rehydration salts are stated to contain the following components: Sodium Chloride 3.5g Potassium Chloride 1.5g Sodium Citrate 2.9g Anhydrous Glucose 20.0g 8.342 g of oral rehydration salts are dissolved in 500 ml of water. 5 ml of the solution is diluted to 100 ml and then 5 ml is taken from the diluted sample and is diluted to 100 ml. The sodium content of the sample is then determined by flame photometry. The sodium salts used to prepare the mixture were: Trisodium citrate hydrate (C6H5Na3O7, 2H2O) MW 294.1 and sodium chloride (NaCl) NW 58.5. Atomic weight of Na = 23. The content of Na in the diluted sample was determined to be 0.3210 mg/100 ml. Determine the % of stated content of Na in the sample. The stated should be 104.5, how??
Oral rehydration salts are stated to contain the following components: Sodium Chloride 3.5g Potassium Chloride 1.5g Sodium Citrate 2.9g Anhydrous Glucose 20.0g 8.342 g of oral rehydration salts are dissolved in 500 ml of water. 5 ml of the solution is diluted to 100 ml and then 5 ml is taken from the diluted sample and is diluted to 100 ml. The sodium content of the sample is then determined by flame photometry. The sodium salts used to prepare the mixture were: Trisodium citrate hydrate (C6H5Na3O7, 2H2O) MW 294.1 and sodium chloride (NaCl) NW 58.5. Atomic weight of Na = 23. The content of Na in the diluted sample was determined to be 0.3210 mg/100 ml. Determine the % of stated content of Na in the sample.
1.063 g of p-acetamidophenol was measured out into a 50 mL round bottom flask along with 8 mL of 1M NaOH in ethanol and a stir bar. This mixture was heated at reflux for 15 min. It was allowed to cool and then 0.80 mL of bromoethane was added to the reaction. The mixture was then heated at reflux for another 15 min. After heating, the solution was poured onto a mixture of ice and water and further cooled on ice and then the solid was collected by vacuum filtration. This solid was then recrystallized from ethanol and water. The final mass of the purified phenacetin was 0.42250 g and it had a melting point of 127 - 130 C. The TLC plate shows (from left to right) pure p-acetamidophenol, the reaction mixture before pouring it on ice/water, phenacetin after recrystallization. The solvent used was a mixture of 80% ethyl acetate and 20% heptane with 0.5% acetic acid added. QUESTION: Using the given TLC plate can you describe the results and what does the TCL plate tell about the purity?
Various parameters in a gas absorption experiment are as follows; Water flow rate =5 L/min, Air flow rate=25 L/min, CO2 flow rate=6 L/min. Then, to find the amount of CO2 absorbed into the water 1 hour after the system is started and stabilized, 50 mL samples are taken from the inlet and outlet of the tank and titrated with 0.01M NaOH. 100mL samples are taken from the tower entrance and exit and sent to the hemp apparatus. The consumptions measured with the help of the Hemp apparatus are 2.1 mL (inlet) and 1.9 mL (output), respectively. According to this, find the amount of CO2 absorbed by titration? (Note: The relative error in the experiment is 10.)
A K2SO4 solution is prepared by weighing out a certain amount of the pure solid reagent,dissolving it to 500.0 mL in a volumetric flask. An aliquot was taken from this solution.of 25.00 ml and diluted to 500.0 ml. An aliquot of 5.00 was taken from this new solution anddiluted to 50.00 ml. A chemical analysis of this new solution showed a 0.100%(w/v)in K+. Calculate the weight of the pure solid K2SO4 used for the preparation of the original solution.and its concentration in each volumetric flask. The answer is 2.23x10^2g
A student weighed approximately 1.5 g of an unknown solid acid and carefully placed the sample in a clean, but not necessarily dry, 250.0 mL volumetric flask. The student added deionized water to the flask, swirled the solution until the solid acid dissolved, then added sufficient deionized water to fill the flask to the fill line. A volumetric pipet was used to transfer 25.00 mL of the resulting solution to an Erlenmeyer flask, and 2 – 3 drops of phenolphthalein were added.The student filled the sodium hydroxide buret and titrated the acid solution with standardized 0.1000 M NaOH to the first permanent faint pink color, then repeated the titration a second time.Your instructor will provide the mass of unknown solid acid, as well as the initial and final buret readings for the two titrations. From this data and the information above, you will be able to calculate the molar mass of the unknown acid.The unknown solid acid is diprotic; that is, there are two moles of ionizable H+ ions per…
A student weighed approximately 1.5 g of an unknown solid acid and carefully placed the sample in a clean, but not necessarily dry, 250.0 mL volumetric flask. The student added deionized water to the flask, swirled the solution until the solid acid dissolved, then added sufficient deionized water to fill the flask to the fill line. A volumetric pipet was used to transfer 25.00 mL of the resulting solution to an Erlenmeyer flask, and 2 – 3 drops of phenolphthalein were added.The student filled the sodium hydroxide buret and titrated the acid solution with standardized 0.1000 M NaOH to the first permanent faint pink color, then repeated the titration a second time.Your instructor will provide the mass of unknown solid acid, as well as the initial and final buret readings for the two titrations. From this data and the information above, you will be able to calculate the molar mass of the unknown acid.The unknown solid acid is diprotic; that is, there are two moles of ionizable H+ ions per…
1. A 4.59 mL sample of HCl, specific gravity 1.3, required 50.5 mL of 0.9544N NaOH in a titration. Calculate the %w/w HCl. 2. A 10 mL sample of sulfuric acid solution required 16.85 mL of NaOH solution in a titration. Each mL of the NaOH solution was equivalent to 0.2477 g of potassium hydrogen phthalate. Calculate the sulfuric acid content in %w/v. MW of sulfuric acid, 98; MW of potassium hydrogen phtalate(KHC8H4O4 ) = 204.22
A brewed tea brand sample was subjected to solvent extraction to extract caffeine. The cup of tea measuring 200 mL was extracted with petroleum ether. With KD = 20.0 (caffeine in pet ether-water), the % caffeine (194.10) extracted after 3 extractions with a total of 75.0 mL pet ether used is: A. 97.7% B. 28.6% C. 71.4% D. 2.33%