A chemist received different mixtures for analysis with the statement that they contained NaOH, NaHCO3, Na2CO3 or compatible mixtures of these substances together with inert material. From the data given, identify the respective materials. Sample 4. The sample was titrated with acid until the pink of phenolphthalein disappeared; this process required 39.96 mL. On adding an excess of the acid, boiling and titrating back with NaOH, it was found that the base was equivalent to the excess acid. A. NazCO3, NaHCO3 В. NaHCOз O C. Na2CO3 O D. None of these OE. NAOH

A chemist received different mixtures for analysis with the statement that they contained NaOH, NaHCO3, Na2CO3 or compatible mixtures of these substances together with inert material. From the data given, identify the respective materials. Sample 4. The sample was titrated with acid until the pink of phenolphthalein disappeared; this process required 39.96 mL. On adding an excess of the acid, boiling and titrating back with NaOH, it was found that the base was equivalent to the excess acid. A. NazCO3, NaHCO3 В. NaHCOз O C. Na2CO3 O D. None of these OE. NAOH

Chemistry

10th Edition

ISBN:9781305957404

Author:Steven S. Zumdahl, Susan A. Zumdahl, Donald J. DeCoste

Publisher:Steven S. Zumdahl, Susan A. Zumdahl, Donald J. DeCoste

Chapter1: Chemical Foundations

Section: Chapter Questions

Problem 1RQ: Define and explain the differences between the following terms. a. law and theory b. theory and...

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A student performed three KHP titrations in Part 1 in order to standardize their NaOH solution. They reported the following measurements: Mass of KHP + Vial Mass of 'Empty' Vial Final Burette Reading Initial Burette Reading Determination #1 16.7538 g 16.2649 g 21.67 mL 0.40 mL Determination #2 14.1709 g 13.5560 g 26.98 mL 0.31 mL Determination #3 15.6625 g 15.0833 g 26.04 mL 0.93 mL How many moles of KHC8H4O4 did they use in their second titration? Report your answer to the correct number of significant figures and only report the numerical value (no units).
100mL of 0.5 M sodium hydroxide was used to completely titrate 150 mL of H3PO4. What was the original molar concentration of the H3PO4 solution?
Number 1_ A 0.5707-g sample of a water-soluble fertilizer was dissolved and analysed for nitrogen using the Kjeldahl method. After digestion, the distilled ammonia was collected in 100 mL of 0.1334 M boric acid. This solution required 26.27 mL of 0.202 M HCl for titration to the methyl red end point. Calculate the % N (AW =14 g/mol) in the fertilizer.
A 0.3749 g soda ash sample is analyzed by titrating sodium carbonate with the standard 0.2388M HCl solution, requiring 49.38ml. The reaction is: CO32- + 2H+ → H2O +CO2Calculate the percent sodium carbonate in the sample.
A student performed three KHP titrations in Part 1 in order to standardize their NaOH solution. They reported the following measurements: Mass of KHP + Vial Mass of 'Empty' Vial Final Burette Reading Initial Burette Reading Determination #1 Determination #2 Determination #3 14.1992 g 14.0219 g 14.0982 g 13.3149 g 13.2301 g 13.2779 g 39.21 mL 0.49 mL 35.46 mL 0.86 mL 37.42 mL 1.59 mL How many moles of NaOH did they use in their third titration? Report your answer to the correct number of significant figures and only report the numerical value (no units).
Calculate the initial concentration of Fe3+, based on the dilution that results from adding KSCN solution and water to the original 0.0020 M Fe(NO3)3solution. See Step 2 of the procedure for the volume of each substance used in Test Tubes 1-4. This value will be the same value for all four test tubes. This is essentially the same as filling out part of the “I” row in an ICE table. Test tube number 0.0020 M Fe(NO3)3(mL) 0.0020M KSCN(mL) H2O(mL) 1 5 2 3 2 5 3 2 3 5 4 1 4 5 5 0
1c
How would your experimentally determined vinegar concentration have differed if the tip of the titrator was not filled with NaOH before the initial volume reading was recorded? Explain your answer.
2. Using the procedure described in this module, a student determined the percent KHP in an impure sample of KHP. A 3.150-g sample of impure KHP required 41.50 mL of 0.1352M NaOH solution for titration. (a) Calculate the number of moles of NaOH required for the titration. (b) Calculate the number of moles of KHP present in the impure sample of KHP. (c) Calculate the number of grams of KHP present in the impure sample. (d) Calculate the percent of KHP in the impure sample, using Equation 8. Equation 8: percent KHP in the impure sample, % = ( mass of KHP in the sample,g/ mass of sample analyzed, g) (100%)
A student performed three H2SO4 titrations in Part 2 using their 0.1048 M NaOH solution which they previously standardized in Part 1. They reported the following measurements: Determination #1 Determination #2 Determination #3 Final NaOH Burette Reading 37.65 mL 28.35 mL 26.23 mL Initial NaOH Burette Reading 12.80 mL 4.05 mL 1.73 mL For every 1 mole of H2SO4, how many moles of NaOH are needed to reach equivalence in the titration? Report the integer number only (no units).
A 2.00 g serum sample is analyzed for protein by the modified Kjeldahl method. The sample is digested and the ammonia is distilled into 50.0 mL of 1.00 M boric acid (FW=61.84 g/mol). A volume of 15.0 mL of standard HCI is required for the titration of the ammonium borate to the methyl orange endpoint. The HCI is standardized by treating 0.330 g of pure sodium carbonate (FW=105.99 g/mol) in the same manner. If 33.3 mL of the acid is required in the standardization process, what is the % protein in the serum? The protein is known to contain 16.0%N. (nitrogen AW=14.01 g/mol)
2b