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Given the balanced chemical equation:

[tex]\[ \text{HC}_2\text{H}_3\text{O}_2(aq) + \text{NaOH}(aq) \longrightarrow \text{NaC}_2\text{H}_3\text{O}_2(aq) + \text{H}_2\text{O}(l) \][/tex]

and the titration data:

[tex]\[
\begin{tabular}{|c|c|c|}
\hline
\text{Trial} & V_i \,(\text{mL}) & V_f \,(\text{mL}) \\
\hline
1 & 4.11 & 16.67 \\
\hline
2 & & \\
\hline
3 & & \\
\hline
\end{tabular}
\][/tex]

For their first trial, a student pipettes 5.00 mL of a vinegar solution into an Erlenmeyer flask. The student titrates the vinegar with standardized NaOH with a molarity of 0.245 M. The volume of titrant used was recorded in the table above. Calculate the molarity of the vinegar solution for this trial. Enter a number without units.

[tex]\[\boxed{\phantom{x}}\][/tex]


Sagot :

To find the molarity of the vinegar solution, let's go through the steps carefully:

1. Initial Volume of Vinegar Solution ([tex]$V_i$[/tex]):
We start with 5.00 mL of vinegar solution.

2. Final Volume of Solution ([tex]$V_f$[/tex]):
The final volume of the solution after titration is recorded as 16.67 mL.

3. Volume of NaOH Titrant Used ([tex]$V_{\text{titrant}}$[/tex]):
The volume of NaOH titrant used during the titration is the difference between the final volume and the initial volume:
[tex]\[ V_{\text{titrant}} = V_f - V_i = 16.67 \, \text{mL} - 5.00 \, \text{mL} = 11.67 \, \text{mL} \][/tex]

4. Molarity of NaOH ([tex]$M_{\text{NaOH}}$[/tex]):
The molarity of the NaOH solution used for titration is given as 0.245 M.

5. Moles of NaOH Used:
To find the moles of NaOH used, we use the volume of NaOH solution (in liters) and its molarity:
[tex]\[ \text{Moles of NaOH} = V_{\text{titrant}} \times M_{\text{NaOH}} = 11.67 \, \text{mL} \times 0.245 \, \text{M} \, \times \frac{1 \, \text{L}}{1000 \, \text{mL}} = 0.00285915 \, \text{moles} \][/tex]

6. Stoichiometry of the Reaction:
The balanced chemical equation shows a 1:1 mole ratio between acetic acid (HC₂H₃O₂) and sodium hydroxide (NaOH). Thus, the moles of acetic acid (HC₂H₃O₂) used are the same as the moles of NaOH:
[tex]\[ \text{Moles of HC}_2\text{H}_3\text{O}_2 = 0.00285915 \, \text{moles} \][/tex]

7. Molarity of Vinegar Solution:
Finally, we determine the molarity of the vinegar solution by dividing the moles of acetic acid by the initial volume of the vinegar solution (in liters):
[tex]\[ \text{Molarity of Vinegar} = \frac{\text{Moles of HC}_2\text{H}_3\text{O}_2}{V_i \, \times \frac{1}{1000}} = \frac{0.00285915 \, \text{moles}}{5.00 \, \text{mL} \times \frac{1 \, \text{L}}{1000 \, \text{mL}}} = 0.57183 \, \text{M} \][/tex]

Therefore, the molarity of the vinegar solution for this trial is [tex]\(0.57183\)[/tex]. Enter this as 0.5718300000000001 without units.