Final answer:
Without the exact data for the reaction involving NaHCO₃ and HC₂H₃O₂, we can't determine the closest to stoichiometric quantities. The example with NaOH and CH₃CO₂H shows that to be stoichiometric, reactants must be in the molar ratio indicated by the balanced equation.
Step-by-step explanation:
To determine which reaction experiment had the closest to stoichiometric quantities, we would need to compare the mole ratios of the reactants to the mole ratios indicated by the balanced chemical equation. In the case provided, assuming that the reaction in question is the reaction of sodium bicarbonate (NaHCO₃) with acetic acid (HC₂,H₃,O₂), we do not have the exact figures for this reaction. However, we can examine the provided data about another reaction involving acetic acid (CH₃CO₂H) and sodium hydroxide (NaOH) to illustrate how to assess stoichiometry.
The balanced chemical equation for the neutralization reaction is:
NaOH(aq) + CH₃CO₂H(aq) → NaCH₃CO₂(aq) + H₂O(l)
In this equation, the stoichiometry shows a 1:1 molar ratio of NaOH to CH₃CO₂H. According to the data, 5.00 mL of a 1.00 mmol/mL NaOH solution was used, so 5.00 mmol of NaOH were present. Since it reacts with CH₃CO₂H in a 1:1 ratio, we initially have 5.00 mmol of CH₃CO₂H. After the reaction, there's an excess of 4.00 mmol CH₃CO₂H, indicating that there was more CH₃CO₂H than NaOH in the mixture, and therefore the mixture was not stoichiometric.
Stoichiometry is important in ensuring that reactions proceed efficiently with minimal waste of reactants. The experiment with the least excess of any reactant after the reaction would be closest to using stoichiometric quantities.
To determine the number of moles of NaHCO₃ and HC₂H₃O₂ in the student's original reaction, one would need the balanced equation and the volumes and concentrations of the solutions used, which is information not provided.