) What four attributes must one have for a primary standard? b) State which chemical used in this lab is the primary standard: ____________ c) Why is necessary to standardize a NaOH solution (instead of taking an accurate mass and diluting it in a volumetric flask and calculating the molarity)?

) What four attributes must one have for a primary standard? b) State which chemical used in this lab is the primary standard: ____________ c) Why is necessary to standardize a NaOH solution (instead of taking an accurate mass and diluting it in a volumetric flask and calculating the molarity)?

Fundamentals Of Analytical Chemistry

9th Edition

ISBN:9781285640686

Author:Skoog

Publisher:Skoog

Chapter17: Complexation And Precipitation Reactions And Titrations

Section: Chapter Questions

Problem 17.16QAP

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1. Do you always have to use a primary standard in the standardization of titrant? Why or why not?
B. Molar Concentration of an Acid Solution Acid type, HA or H,A: HA Unknown No. Balanced equation for neutralization of acid with NaOH. NaOH + HCI = NaCI + Sample 1 Sample 2 Sample 3 1. Volume of acid solution (mL) 25.0 25.0 25.0 2. Buret reading of NaOH, initial (mL) 0.00 0.00 0.00 3. Buret reading of NaOH, final (mL) 26.3 26.0 26.8 26.3 26.0 0.148 4. Volume of NaOH dispensed (mL) 26.8 5. Molar concentration of NAOH (mol/L), Part A 6. Moles of NaOH dispensed (mol) 7. Molar concentration of acid solution (mol/L) 8. Average molar concentration of acid solution (mol/L) Data Analysis, B 9. Standard deviation of molar concentration Data Analysis, C 10. Relative standard deviation of molar concentration (%RSD) Data Analysis, D
Part 1: Preparation of the Primary Citric Acid Standard 1. Mass of Citric Acid: 4.05 g 2. Volume of Citric Acid Solution: 0.75 ml (at the equivalence point) 3. Moles of Citric Acid: (Molar Mass = 192.0 g/mol) 4. Molarity of Citric Acid Solution: Part 2: Titration of the Sodium Hydroxide Solution (Show your work on page 4) 1. Volume of Citric Acid at the Equivalence Point 2. Moles of Citric Acid at the Equivalence Point: 3. Moles of NaOH at the Equivalence Point 3 NaOH + H.CaHsO, → Na:CH.O, + 3 H,O 4. Volume of NaOH 10.0 mL 5. Calculated Molarity of NaOH: Do not use the dilution equation to calculate the molarity of the sodium hydroxide. The dilution equation cannot be used when a reaction is occurring
1. Molarity of the NaOH solution 0.238 mol/L Trial 1 Trial 2 Trial 2. Volume of H;PO4 added to flask 22.0 mL 22.0 mL 22.0 mL 3. Initial NaOH volume _0.25_ mL _0.75_ mL 0.55 mL 4. Final NaOH volume 17.60_ mL 18.20_ mL _17.90_ mL 5. NAOH volume used for titration to reach green end point mL mL mL 6. NaOH volume used for titration 7. Moles of NaOH used for titration mol mel mel 8. Moles of H;PO4 that reacted mol mel mol 9. Volume of H;PO4 added to flask L 10. Molarity of H3PO4 mol/L mol/L mol/L
What is the concentration of a standardized HCl solution that required 50.78 mL of HCl to titrate 0.7682 g of a primary standard Na2CO3? Na2CO3 + 2HCl --> H2CO3 + 2NaCl Na2CO3 = 105.99 g/mol ROUND OFF FINAL ANSWER TO FOUR (4) SIG FIGS.
In the experiment, the amount of acetic acid in vinegar was determined by titrating with 0.1 M NaOH solution. In the analysis, three trials were performed to obtain more precise result. The table shows the initial and final burette readings for three titrations: Initial Burette Reading (mL) Final Burette Reading (mL) Trial 1 2.9 10.6 Trial 2 10.6 18.1 Trial 3 18.1 25.7 According to the given data, calculate molarity of acetic acid in the commercial vinegar. Please be sure that your answer includes followings; a) moles of NaOH for each trial b) average mole of NaOH c) average mole of acetic acid in 50 mL solution d) average mole of acetic acid in 250 mL solution e) molarity of acetic acid in vinegar.
Which of the following steps MUST be done prior to titration of an analyte? I. Prepare a standardized solution II. Wash the burette with a standardized solution III. Fill the burette to the 50-mL mark IV. Prepare a contrast paper to determine burette volume and titration endpoint
What happens when a non-standard titrant is used in the titration of an unknown sample?a - The volume of the acid used will not be accurate.b - The normality of the acid used will not be accurate.c - The weight of the analyte will not be accurate.d - It will not matter.
Quantity Your Data 1. Grams of vinegar sample used for your titration 25.000 g 2. Initial Buret Reading of Sodium Hydroxide solution 10.00 mL 3. Final Buret Reading of Sodium Hydroxide solution 28.00 mL 4. Amount of Sodium Hydroxide Solution used to neutralize the vinegar sample 5. Concentration of NaOH in the NaOH solution 0.050 g/mL 6. Grams of NaOH used to neutralize the vinegar 7. Grams of acetic neutralized by the amount of NaOH 8. Percent acetic acid in the vinegar Hints: For #4, The amount of NaOH used is the difference between the starting buret value and the ending buret value. For #6, Once you calculate the amount of sodium hydroxide used, multiple that value by the concentration of NaOH in the NaOH solution. For #7, Multiply the value obtained in number 6 by the number 1.5. Remember, we learned that every 1 gram of NaOH neutralizes 1.5 grams of acetic acid. For #8, Divide the grams of acetic acid by the grams of vinegar sample and multiply this value by…
Part A) A 10.0 mL sample of 0.250 mol/L NiF2(aq) is mixed with 20.0 mL of 0.0900 mol/L NaOH(aq) and then diluted to a final volume of 100. mL.Calculate the concentration of Ni2+ ions in the 100 mL mixture before the reaction starts. Express your answer to three significant figures.ksp: 5.48e-16
You want to make a solution of the primary standard sodium oxalate. It has a molecular mass of 133.999 g/mol (no error). Your analytical balance has an error of 0.2 mg. You add some weighing paper to the balance and it reads a mass of 0.23626 g. You then add sodium oxalate onto the weighing paper until the mass registers as 2.8539 g. You carefully transfer this to a 250.0 ml volumetric flask with an error of 0.1 ml and dissolve the sodium oxalate in a sufficient volume of water. What is the concentration of the oxalic acid (in M) and what is the absolute error (also in M).
For problem 5, the density of the sample is 0.9977 g/ml. and the molar mass of calcium carbonate is 100.0 g/mol. 5. As described in Topic 2 in the lab manual, the hardness of water is expressed in terms of amount of calcium carbonate according to the ppm expression. Calculate the mass of calcium carbonate present in a 50.00 mL sample of an aqueous calcium carbonate standard, assuming the standard is known to have a hardness of 75.0 ppm (hardness du to CaCO;). a. b. Calculate the number of moles of calcium ions present in this 50.00 mL sample of aqueous calcium carbonate standard. C. The 50.00 mL sample (at pH 10) was titrated with a 0.00500 M EDTA solution, Write the balance net ionic equation for the reaction of EDTA“ with a calcium ion. Calculate the number of moles of EDTA“ needed to completely react with calcium ions in the sample. What volume (in milliliters) of EDTA solution would be needed to reach the equivalence point?