Passage
Although acetylsalicylic acid (aspirin) is a well-known and widely used analgesic and anti-inflammatory agent, copper(II) acetylsalicylate, a copper complex formed from aspirin and copper, has also been found to exhibit some distinctive and potentially beneficial pharmacological properties. Formation of copper(II) acetylsalicylate is achieved when the conjugate base of aspirin, acetylsalicylate (C₉H₇O₄⁻) , binds to Cu²⁺ ions in solution, as outlined in Reaction 1.4 NaC₉H₇O₄(aq) + 2 CuSO₄(aq) → Cu₂(C₉H₇O₄) ₄(s) + 2 Na₂SO₄(aq) Reaction 1Using Reaction 1, a researcher synthesized a sample of copper(II) acetylsalicylate for analysis. A small volume of 0.50 M aqueous copper(II) sulfate (molar mass = 159.6) was mixed into 100 mL of filtered, saturated aqueous sodium acetylsalicylate (molar mass = 202.2) at room temperature and slowly stirred. Formation of copper(II) acetylsalicylate (molar mass = 843.7) was immediately observed as a bright blue precipitate. The precipitate was then isolated by filtration and dried, affording the product complex in high yield.
Adapted from: Seguel GV, Rivas BL, Contreras JG. Synthesis and characterization of copper complexes: interaction of metalliccarboxylates with 1,3-thiazole ligand. Journal of the Chilean Chemical Society. 1970; 58(4) :1967.
-In the reaction, just prior to precipitation, what is the ratio of the concentration of copper(II) acetylsalicylate to the concentration of sodium sulfate?

Question

Quizplus · Accepted Answer

11ecba2d_11cc_9f3c_a3bf_a9b84378d251_MD0008_00 Chemical compounds react in definite proportions (ratios) during a chemical reaction. The coefficients in front of each chemical formula in a balanced chemical reaction indicate the stoichiometric mole ratios by which each chemical combines during the reaction. Therefore, mole ratios derived from these coefficients can be used as conversion factors in chemical reaction calculations to relate the molar amount of one substance to the molar amount of another in a reaction. Accordingly, these ratios also relate the concentration of one product to that of another for a given reaction volume. Reaction 1 shows that there will be 2 moles of Na₂SO₄ produced for every 1 mole of Cu₂(C₉H₇O₄)₄ produced within the same solution volume. Therefore, the molar concentration of Cu₂(C₉H₇O₄)₄ equals half the molar concentration of Na₂SO₄, and a reaction that produces n moles of Na₂SO₄ per liter of solution will produce n/2 moles of Cu₂(C₉H₇O₄)₄. As a result, the Cu₂(C₉H₇O₄)₄ concentration (prior to precipitation) is equal to half the Na₂SO₄ concentration. (Choice A) A ratio of 1/4 corresponds to the mole ratio between Cu₂(C₉H₇O₄)₄ and the NaC₉H₇O₄ reactant instead of between Cu₂(C₉H₇O₄)₄ and Na₂SO₄. (Choice C) A ratio of 2/2 corresponds to the mole ratio between the Na₂SO₄ product and the CuSO₄ reactant instead of between Cu₂(C₉H₇O₄)₄ and Na₂SO₄. (Choice D) A ratio of 2/1 is the mole ratio of Na₂SO₄ to Cu₂(C₉H₇O₄)₄, rather than the ratio of the mole ratio of Cu₂(C₉H₇O₄)₄ to Na₂SO₄ (the ratio has been flipped). Educational objective: The coefficients in a balanced chemical reaction indicate the stoichiometric proportions by which each chemical combines during the reaction. Mole ratios derived from these coefficients can be used as conversion factors in chemical reaction calculations to relate the molar amounts of compounds in a reaction.

Passage Although Acetylsalicylic Acid (Aspirin) Is a Well-Known and Widely Used