Solution Concentration Mass percent mass partmass whole x

Solution Concentration Mass percent • (mass part/mass whole) x 100(%) • An aqueous solution of acetic acid is 20 percent by weight Acetic acid has a density of 1. 0269 g/m. L. How many moles of acetic acid are contained in 35 m. L of this solution? Practice problem Tro – 4. 55

Solution Concentration Molarity (M) • Mole solute/ Liter solution • For Dilution -- M 1 V 1 = M 2 V 2 – A chemist wants to prepare 0. 25 M HCl. Commercial HCl is 12. 4 M. How many m. L of the concentrated acid does the chemist require to make up 1. 50 L of the dilute acid? Practice problems Tro – 4. 59 -4. 62

Solution Concentration Molarity (M) • Conversion of % to molarity – A 35. 0% solution of glucose (C 6 H 12 O 6) has a density of 1. 28 g/m. L. What is the molarity of the solution? Practice problems Tro – 4. 95 -4. 96

Solution Stoichiometry • Some sulfuric acid is spilled on a lab bench. It can be neutralized by sprinkling sodium bicarbonate on it and then mopping up the resultant solution. The sodium bicarbonate reacts with sulfuric acid as follows: • 2 Na. HCO 3(s) + H 2 SO 4(aq) Na 2 SO 4(aq) + 2 H 2 O(l) + 2 CO 2(g) • Sodium bicarbonate is added until the fizzing due to the formation of CO 2(g) stops. If 27 m. L of 6. 0 M H 2 SO 4 was spilled, what if the minimum mass of Na. HCO 3 that must be added to the spill to neutralize the acid?

Solution Stoichiometry • 581 m. L of 0. 342 M Barium nitrate [Ba(NO 3)2] are mixed with 264 m. L of 0. 631 M potassium sulfate (K 2 SO 4). Write the molecular, ionic, and net ionic reactions for this reaction, calculate the mass of any precipitate produced and inventory the ions in solution after precipitation. Practice problems Tro – 4. 116

• A 35. 49 m. L sample of 0. 2430 M H 2 SO 4 is mixed with 65. 33 m. L of a 0. 4199 M sample of KOH. Determine the concentration of all ions in solution, the p. H, and p. OH. Remember p. H = -log [H 3 O+] = 10 -p. H p. OH = -log [OH-] = 10 -p. OH p. H + p. OH = 14 [H 3 O+][OH-]=10 -14 M 2

Titrations • A noncarbonated soft drink contains an unknown amount of citric acid, H 3 C 6 H 5 O 7. If 100. 0 m. L of the soft drink requires 33. 51 m. L of 0. 01024 M Na. OH to neutralize the citric acid completely, what is the concentration of citric acid in the soft drink in moles/liter (M)? In equivalents/liter (N)? Practice problems Tro – 4. 84, 4. 110

Titrations • Suppose you are given a 4. 554 g sample that is a mixture of oxalic acid, H 2 C 2 O 4, and another solid that does not react with sodium hydroxide. If 29. 58 m. L of 0. 5501 M Na. OH is required to titrate the oxalic acid in the 4. 554 g sample, what is the weight percent of oxalic acid in the mixture?

• An unknown solid acid is either citric acid or tartaric acid. To determine which acid you have, you titrate a sample of the solid with aqueous Na. OH and from this determine the molar mass of the unknown acid. A 0. 956 g sample was titrated with 29. 1 m. L of 0. 513 M Na. OH. The formulas for the acids are • Citric acid H 3 C 6 H 5 O 7 • Tartaric acid H 2 C 4 H 4 O 6

• The molar mass of a certain metal carbonate, MCO 3, can be determined by adding an excess of HCl acid to react with all the carbonate and then “back titrating” the remaining acid with a Na. OH solution. • Write the equations for these reactions • In a certain experiment, 20. 00 m. L of 0. 0800 M HCl were added to a 0. 1022 g sample of MCO 3. The excess HCl required 5. 64 m. L of 0. 1000 M Na. OH for neutralization. Calculate the molar mass of the carbonate and identify M.

Challenge Problem • A 19. 264 gram sample of a mixture of Mg. Cl 2 and Cs. Cl is dissolved in water and treated with excess Ag. NO 3 so that ALL the chloride precipitates as Ag. Cl. The mass of dried Ag. Cl is 43. 668 grams. Calculate the mass Cs. Cl in the sample.