a. The reaction between hydrochloric acid and sodium carbonate is given by the equation 2 HCI (aq) + Na2CO3 (aq) 2 NaCI (aq) + H2O (1) + CO2 (g) If 25.00 mL of 0.05000 M sodium carbonate solution is neutralized by 32.45 mL of hydrochloric acid, determine the concentration of the hydrochloric acid. b. 0.4201 g of an unknown monoprotic acid was dissolved in 25.00 mL of water and titrated with 0.09995 M NaOH. It was found that 38.76 mL of NaOH was required to reach the equivalence point. Determine the molecular weight of this unknown acid.

a. The reaction between hydrochloric acid and sodium carbonate is given by the equation 2 HCI (aq) + Na2CO3 (aq) 2 NaCI (aq) + H2O (1) + CO2 (g) If 25.00 mL of 0.05000 M sodium carbonate solution is neutralized by 32.45 mL of hydrochloric acid, determine the concentration of the hydrochloric acid. b. 0.4201 g of an unknown monoprotic acid was dissolved in 25.00 mL of water and titrated with 0.09995 M NaOH. It was found that 38.76 mL of NaOH was required to reach the equivalence point. Determine the molecular weight of this unknown acid.

Chemistry: The Molecular Science

5th Edition

ISBN:9781285199047

Author:John W. Moore, Conrad L. Stanitski

Publisher:John W. Moore, Conrad L. Stanitski

Chapter3: Chemical Reactions

Section: Chapter Questions

Problem 93QRT: A soft drink contains an unknown mass of citric acid, C3H5O(COOH)3. It requires 6.42 mL of 9.580 ×...

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A soft drink contains an unknown mass of citric acid, C3H5O(COOH)3. It requires 6.42 mL of 9.580 × 10−2-M NaOH to neutralize the citric acid in 10.0 mL of the soft drink. C3H5O(COOH)3(aq) + 3 NaOH(aq) → Na3C3H5O(COO)3(aq) + 3 H2O(ℓ) Determine which step in these calculations for the mass of citric acid in 1 mL soft drink is incorrect? Why? n (NaOH) = (6.42 mL)(1L/1000 mL)(9.580 × 10−2 mol/L) n (citric acid) = (6.15 × 10−4 mol NaOH) × (3 mol citric acid/1 mol NaOH) m (citric acid in sample) = (1.85 × 10−3 mol citric acid) × (192.12 g/mol citric acid) m (citric acid in 1 mL soft drink) = (0.354 g citric acid)/(10 mL soft drink) Determine the correct result.
It is stated in Section 6.3 of the text that to balance equations by inspection you start “with the most complicated molecule.” What does this mean? Why is it best to do this?
A student wants to prepare 1.00 L of a 1.00-M solution of NaOH (molar mass = 40.00 g/mol). If solid NaOH is available, how would the student prepare this solution? If 2.00 M NaOH is available, how would the student prepare the solution? To help ensure three significant figures in the NaOH molarity, to how many significant figures should the volumes and mass be determined?
Two beakers sit on a balance; the total mass is 167.170 g. One beaker contains a solution of KI; the other contains a solution of Pb(NO3)2. When the solution in one beaker is poured completely into the other, the following reaction occurs: 2 KI(aq) + Pb(NO3)2(aq) 2 KNO3(aq) + PbI2(s) What is the total mass of the beakers and solutions after reaction? Explain completely.
On Easter Sunday, April 3, 1983, nitric acid spilled from a tank car near downtown Denver, Colorado. The spill was neutralized with sodium carbonate: 2HNO3(aq)+Na2CO3(aq)2NaNO3(aq)+H2O(l)+CO2(g) a. Calculate H for this reaction. Approximately 2.0 104 gal nitric acid was spilled. Assume that the acid was an aqueous solution containing 70.0% HNO3 by mass with a density of 1.42 glcm3. What mass of sodium carbonate was required for complete neutralization of the spill, and what quantity of heat was evolved? (Hf for NaNO3(aq) = 467 kJ/mol) b. According to The Denver Post for April 4, 1983, authorities feared that dangerous air pollution might occur during the neutralization. Considering the magnitude of H, what was their major concern?
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A student mixes four reagents together, thinking that the solutions will neutralize each other. The solutions mixed together are 50.0 mL of 0.100M hydrochloric acid, 100.0 mL of 0.200 M of nitric acid, 500.0 mL of 0.0100 M calcium hydroxide, and 200.0 mL of 0.100 M rubidium hydroxide. Did the acids and bases exactly neutralize each other? If not, calculate the concentration of excess H+ or OH ions left in solution.
list at least three quantities that must be conserved in chemical reactions.
Potassium permanganate (KMnO4) solutions are used for the determination of Fe2+ in samples of unknown concentration. As a laboratory assistant, you are supposed to prepare 500 mL of a 0.1000 M KMnO4 solution. What mass of KMnO4, in grams, do you need?
3.86 When a solution is diluted, solvent is added but solute is not. Explain how this idea leads to the equation frequently used in dilution calculations, M1V1= M2V2.
Two students titrate different samples of the same solution of HCl using 0.100 M NaOH solution and phenolphthalein indicator (Figure 4.12). The first student pipets 20.0 mL of the HCl solution into a flask, adds 20 mL of distilled water and a few drops of phenolphthalein solution, and titrates until a lasting pink color appears. The second student pipets 20.0 mL of the HCl solution into a flask, adds 60 mL of distilled water and a few drops of phenolphthalein solution, and titrates to the first lasting pink color. Each student correctly calculates the molarity of an HCl solution. What will the second students result be? (a) four times less than the first students result (b) four times greater than the first students result (c) two times less than the first students result (d) two times greater than the first students result (e) the same as the first students result