An approximately 0.1 M NaOH solution is made by adding 4.0 g of solid NaOH to 1000 mL. of water. The precise concentration of the solution is determined by titrating the NaOH against portions of a weak acid, potassium acid phthalate (KHP) obtained from the National Bureau of Standards and certified as being 99.99% pure. The KHP samples are weighed by difference on a balance. How would the calculated NaOH concentration be affected (in comparison with the true concentration), if: (does it become greater, smaller, or unchanged) 1. The KHP was not dried prior to weighing? 2. The balance always read high, but in proportion to the weight recorded?

An approximately 0.1 M NaOH solution is made by adding 4.0 g of solid NaOH to 1000 mL. of water. The precise concentration of the solution is determined by titrating the NaOH against portions of a weak acid, potassium acid phthalate (KHP) obtained from the National Bureau of Standards and certified as being 99.99% pure. The KHP samples are weighed by difference on a balance. How would the calculated NaOH concentration be affected (in comparison with the true concentration), if: (does it become greater, smaller, or unchanged) 1. The KHP was not dried prior to weighing? 2. The balance always read high, but in proportion to the weight recorded?

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...

See similar textbooks

Similar questions

One way in which the useful metal copper is produced is by dissolving the mineral azurite, which contains copper(II) carbonate, in concentrated sulfuric acid. The sulfuric acid reacts with the copper(II) carbonate to produce a blue solution of copper(II) sulfate. Scrap iron is then added to this solution, and pure copper metal precipitates out because of the following chemical reaction: Fe(s)+CuSO4(aq)→Cu(s)+FeSO4(aq) Suppose an industrial quality-control chemist analyzes a sample from a copper processing plant in the following way. He adds powdered iron to a 350.mL copper(II) sulfate sample from the plant until no more copper will precipitate. He then washes, dries, and weighs the precipitate, and finds that it has a mass of 142.mg. Calculate the original concentration of copper(II) sulfate in the sample. Be sure your answer has the correct number of significant digits.
6. A student titrated 30.00 mL of a hydrochloric acid solution with 1.00 M sodium hydroxide. The sodium hydroxide was initially tilled to the 2.30 mL mark on the burette. Once the level in the burette reached 50.00 mL, the student was forced to refill the burette and did so to the 5.06 mL mark. The endpoint was finally reached when the sodium hydroxide level dropped to 32.09 mL on the burette. What is the molarity of the acid solution? Show work.
One way in which the useful metal copper is produced is by dissolving the mineral azurite, which contains copper(II) carbonate, in concentrated sulfuric acid. The sulfuric acid reacts with the copper(II) carbonate to produce a blue solution of copper(II) sulfate. Scrap iron is then added to this solution, and pure copper metal precipitates out because of the following chemical reaction: Fe (s) + CuSO4 (aq) → Cu (s) + FeSO4 (aq)Suppose an industrial quality-control chemist analyzes a sample from a copper processing plant in the following way. He adds powdered iron to a 200.mL copper(II) sulfate sample from the plant until no more copper will precipitate. He then washes, dries, and weighs the precipitate, and finds that it has a mass of 73.mg . Calculate the original concentration of copper(II) sulfate in the sample. Be sure your answer has the correct number of significant digits.
One way in which the useful metal copper is produced is by dissolving the mineral azurite, which contains copper(II) carbonate, in concentrated sulfuric acid. The sulfuric acid reacts with the copper(II) carbonate to produce a blue solution of copper(II) sulfate. Scrap iron is then added to this solution, and pure copper metal precipitates out because of the following chemical reaction: Fe(s) + CuSO4(aq) → Cu(s) + FeSO4 (aq) Suppose an industrial quality-control chemist analyzes a sample from a copper processing plant in the following way. He adds powdered iron to a 350. mL copper(II) sulfate sample from the plant until no more copper will precipitate. He then washes, dries, and weighs the precipitate, and finds that it has a mass of 111. mg. Calculate the original concentration of copper(II) sulfate in the sample. Be sure your answer has the correct number of significant digits. 0-2 X 5
1 Hydrogen peroxide solutions can easily be decomposed by dust, trace amounts of metals or light. It is therefore necessary to periodically determine the purity of the peroxide solutions. This can be done via a redox titration as follows: • The density of a particular surgical grade hydrogen peroxide solution is 1.11g.cm³. • Exactly 10 mL of this solution was pipetted and quantitatively transferred, along with a sufficient amount of a dilute sulphuric acid solution, into a 250.00 mL volumetric flask and made up to the mark. • A 25.00 mL portion of this diluted solution is pipetted into a conical flask, and titrated with a 0.372 M KMNO4 solution. • The endpoint of the titration is determined when the colourless solution in the conical flask turns a persistent bright pink due to the presence of excess permanganate ions. • The average titration value is 26.20 mL of the KMNO4 solution. The reaction stoichiometry is as follows: 2KMN0,(aq) + 3H280,(aq) + 5H20, (aq) → 2MNS0,(aq) + K2s0,(aq) +…
A sample with a mass of 1.340 g was dissolved in water, releasing chlorine ions. The aqueous solution was treated with access AgNO3(aq), the AgCl precipitate collected and weighted. Its mass was 2.709 g. What percentage by mass was the original sample? Make sure to use the correct number of significant figures in your answer.
Suppose a student performs a similar reaction using sodium bicarbonate (NaHCO3) instead of sodium carbonate. The sodium bicarbonate is dissolved in water, and a solution of 6.0 M HCl is added to the sodium bicarbonate in increments. Bubbles are observed during the reaction. The data collected is shown in the table. moles of NaHCO3: mass of empty beaker (g) moles of NaCl: mass of beaker and NaHCO3 (g) initial volume of 6.0 M HCl (mL) How many moles of NaHCO3 were used? balanced equation: final volume of 6.0 M (ml) mass of beaker and NaCl (g) How many moles of NaCl were produced by the reaction? Write the balanced chemical equation for the reaction. Include physical states. 84.000 g 86.279 g 20.0 mL 12.0 mL 85.585 g mol mol
One way in which the useful metal copper is produced is by dissolving the mineral azurite, which contains copper(II) carbonate, in concentrated sulfuric acid. The sulfuric acid reacts with the copper(II) carbonate to produce a blue solution of copper(II) sulfate. Scrap iron is then added to this solution, and pure copper metal precipitates out because of the following chemical reaction: Fe (s) + CuSO4 (aq) → Cu (s) + FeSO4 (aq)Suppose an industrial quality-control chemist analyzes a sample from a copper processing plant in the following way. He adds powdered iron to a 300.mL copper(II) sulfate sample from the plant until no more copper will precipitate. He then washes, dries, and weighs the precipitate, and finds that it has a mass of 67.mg . Calculate the original concentration of copper(II) sulfate in the sample. Be sure your answer has the correct number of significant digits.
One way in which the useful metal copper is produced is by dissolving the mineral azurite, which contains copper(II) carbonate, in concentrated sulfuric acid. The sulfuric acid reacts with the copper(II) carbonate to produce a blue solution of copper(II) sulfate. Scrap iron is then added to this solution, and pure copper metal precipitates out because of the following chemical reaction: Fe (s) + CuSO4 (aq) → Cu (s) + FeSO4 (aq)Suppose an industrial quality-control chemist analyzes a sample from a copper processing plant in the following way. He adds powdered iron to a 500.mL copper(II) sulfate sample from the plant until no more copper will precipitate. He then washes, dries, and weighs the precipitate, and finds that it has a mass of 76.mg . Calculate the original concentration of copper(II) sulfate in the sample. Be sure your answer has the correct number of significant digits. gL
One method for chemical analysis involves finding a reactant that will precipitate the species of interest, but not the other species. The mass of the precipitate is then used to determine the mass of the species of interest present in the original sample. For example, calcium ions can be precipitated from an aqueous solution by adding of sodium oxalate Na2C2O4. The balanced equation is: Ca2+(aq) + Na2C2O4 (aq) --> CaC2O4 (s) + 2 Na+ (aq) Suppose you had a solution with approximately 15.0 g of calcium ions. Show by calculation whether the addition of 15.0 g of sodium oxalate will precipitate all of the calcium ions present in the sample.
A chemist needs to determine the concentration of a sulfuric acid solution by titration with a standard sodium hydroxide solution. He has a 0.1840 M standard sodium hydroxide solution. He takes a 25.00 mL sample of the original acid solution and dilutes it to 250.0 mL. Then, he takes a 10.00 mL sample of the dilute acid solution and titrates it with the standard solution. The endpoint was reached after the addition of 13.34 mL of the standard solution. What is the concentration of the original sulfuric acid solution? concentration: M
One way in which the useful metal copper is produced is by dissolving the mineral azurite, which contains copper(II) carbonate, in concentrated sulfuric acid. The sulfuric acid reacts with the copper(II) carbonate to produce a blue solution of copper(II) sulfate. Scrap iron is then added to this solution, and pure copper metal precipitates out because of the following chemical reaction: Fe(s) + CuSO (aq) → Cu(s) + FESO,(aq) Suppose an industrial quality-control chemist analyzes a sample from a copper processing plant in the following way. He adds powdered iron to a 200. mL copper(II) sulfate sample from the plant until no more copper will precipitate. He then washes, dries, and weighs the precipitate, and finds that it has a mass of 64. mg. Ar Calculate the original concentration of copper(II) sulfate in the sample. Round your answer to 2 significant digits. 10