To a 0.5 g sample of impure NaCl are added 0.784 g of pure AgNO3 (MW = 169.88) crystal. This is in excess of the amount required to ppt. All the Cl as AgCl. After dissolving and filtering out the pptd. AgCl, the filtrate requires 25.50 ml of 0.028M KCNS. What is the percentage of NaCl (MW=58.44) in the sample? A. 55.40 % B. 50.10% C. 45.60% D. 100%

To a 0.5 g sample of impure NaCl are added 0.784 g of pure AgNO3 (MW = 169.88) crystal. This is in excess of the amount required to ppt. All the Cl as AgCl. After dissolving and filtering out the pptd. AgCl, the filtrate requires 25.50 ml of 0.028M KCNS. What is the percentage of NaCl (MW=58.44) in the sample? A. 55.40 % B. 50.10% C. 45.60% D. 100%

EBK A SMALL SCALE APPROACH TO ORGANIC L

4th Edition

ISBN:9781305446021

Author:Lampman

Publisher:Lampman

Chapter2: Crystallization

Section: Chapter Questions

Problem 3Q

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To a 0.5 g sample of impure NaCl are added 0.784 g of pure AgNO3 (MW = 169.88) crystal. This is in excess of the amount required to ppt. All the Cl as AgCl. After dissolving and filtering out the pptd. AgCl, the filtrate requires 25.50 ml of 0.28M KCNS. What is the percentage of NaCl (MW=58.44) in the sample?
The standard addition method is used to analyze a sample of a river water for mercury. Solution A is made by pipetting 5.00 mL of undiluted sample in to a 10 mL volumetric flask and filling to the mark with DI water. Solution B is made by pipetting 5.00 mL of undiluted sample and 3.00 mL of 15.0 ppb of Hg standard into same 10.0 mL volumetric flask and filling to the mark with DI. Solution A and B are analyzed using atomic absorption spectroscopy and give a percent transmittance values of 56 % and 33 % respectively (not blank corrected). A blank has a transmittance of 96%. What is the corrected absorbance of both solution A and B? A. Solution A: 0.123 Solution B: 0.463 B. Solution A: 0.463 Solution B: 0.234 C. Solution A: 0.123 Solution B: 0.234 D. Solution A: 0.234 Solution B: 0.463
An impure sample of calcium carbonate with a mass of 7.95 g was reacted with 50.00 cm3 of 1.00 mol dm hydrochloric acid (an excess). The resulling solution was transferred to a volumetric flask and titrated with 11.10cm3 of 0.300 mol dm-3 sodium hydroxide solution. Determine the percentage purity by mass of the calcium carbonate sample.CaCO3 + HCl -> CaCl2 + H2O + CO2 HCl + NaOH -> NaCl +H2O a. Determine how many moles of hydrochloric acid were used.b. Determine how many moles of excess HCI was titratedc. Determine how much in moles calcium carbonate present in the sample.d. Calculate the mass of calcium carbonate presente. Determine the percentwge calcium carbonate is in the sample.
Aspirin powder = 0.8110g MW of Aspirin = 180g.mol-1 Volume of 0.5N HCl consumed in back titration = 23.50mL Volume of 0.5N HCl consumed in blank titration = 44.50mL Percent purity (USP/NF) = Aspirin tablets contain NLT 90.0% and NMT 110.0% of the labeled amount of aspirin (C9H8O4) What is the calculated weight (in grams) of pure aspirin?..
Measure the mass of 0.400g of Co(NO3)2 + 6H2O and dissolve it in 15mL of distilled or deionized water using a clean beaker Then while using a graduated cylinder, measure out 10.0mL of a prepared 0.10-M Na3PO4 soultion. Determine which compound Na3PO4 or Co(NO3)2 *6H2O will be the limliting reagent. Then detrimine the theiretical yeild
The solubility of borax, which is made up of sodium tetraborate (Na2B4O5(OH)4 8H2O), was analyzed. The dissolution of borax is: Na2B4O5(OH)4 • 8H2O(s) ⇌ 2 Na+(aq) + B4O5(OH)42–(aq) + 8 H2O(l) A 50 mL saturated solution was prepared. After filtration of solution, 5 mL aliquot was transferred to a flask and titrated using 0.432 M HCl. The endpoint was found to be 4.73 mL of the titrant. Tetraborate anion (B4O5(OH)42-) is a weak base which reacts with HCl like the following reaction: B4O5(OH)42–(aq) + 2 H+(aq) + 3 H2O(l) ⇌ 4 H3BO3(aq) What is Ksp expression for the dissolution? What is the tetraborate ions concentration in the filtrate? What is the molar solubility and Ksp of borax if the titration was done at room temperature (298 K)?
Consider the titration illustrated in Figure 8.] Anhydrous sodium carbonate (Na₂CO₃) is a primary standard. When 0.364 grams of the substance is placed in a conical flask, then 20.00 cm³ of sulphuric acid (H₂SO₄) solution is required to reach the end point of the titration. What is the concentration in mol·dm⁻³ of the sulphuric acid solution? [Give the answer to 3 decimal places. Do not type in the unit. Use a decimal point.] *
1. What is the MW of the analyte?2. What is the meq of the analyte?3. What will be the weight (in grams) of the analyte if the standardization is to be quartered?4. What will be Normality of the solution if 7.5ml of the titrant was consumed in the standardization?5. What is the average Normality if two or more trials were conducted with the values of 0.102N and 0.105N?
A sample containing iron is approximately 99.0% w/w Fe. Using ammonia, iron is precipitated as Fe (OH)3 which is ignited to Fe203. (a) What is the gravimetric factor for analyte Fe (AW=55.85 g/mol) and precipitate Fe203 (FW=159.69 g/mol)? (b) What mass of sample is needed to ensure that the Fe203 precipitate would weigh at least 1.00 g?
Gravimetric analysis of Fe3O4 (MW = 232 g/mole) may be undertaken with the following reactions: Fe3O4 → Fe2O3 → Fe (OH)3. Weight of sample containing 8.00% Fe3O4 that must be taken to obtain a precipitate of Fe(OH)3 (MW = 107 g/mole) that weighs 150 mg is . a. 0.108 g b. 0.325 g c. 1.355 g d. 4.065 g Amount of Fe2O3 (MW = 160 g/mole) from which 150 mg of Fe(OH)3 (MW = 107 g/mole) may be obtained is . a. 0.112 g b. 0.224 g c. 0.448 g d. none of the other choices
A 0.1093-g sample of impure Na2CO3( Molecular weight 106) was analyzed by the Volhard method. After adding 50.00 mL of 0.06911 M AGN03 (Molecular weight 169.87), the sample was back titrated with 0.05781 M KSCN, requiring 27.36 mL to reach the end point. Report the purity of the Na2CO3 sample.
A 0.1475-M solution of Ba(OH)2 was used to titrate the acetic acid (60.05 g/mol) in a dilute aqueous solution. The following results were obtained. (See attached image)(a) Calculate the mean w/v percentage of acetic acid in the sample.(b) Calculate the standard deviation for the results.(c) Calculate the 90% confidence interval for the mean.(d) (d) At the 90% confidence level, could any of the results be discarded?