Question

Data Analysis C. Transfer the hydronium concentration, [H3O+] from Table 2 to Table 3 for each sample. Based the measured hydronium concentration in Table 2, infer the concentration of C2H302. For each solution above, considering the amount of HC2H2O2 that must have ionized to give the measured concentration of [H3O+] and the stated concentration of HC2H2O2, calculate the remaining concentration of HC H:02. Record those values in Table 3 for each solution. Show the details of the calculations in your laboratory notebook.

Answer 1

In all of these cases, I assume that HC₂H₃O₂ was added to all solutions. This means that the following equilibrium was established:

$HC_{2}H_{3}O_{2}+H_{2}O\leftrightharpoons C_{2}H_{3}O_{2}^{-}+H_{3}O^{+}$

This means that, necessarily, the concentration of C₂H₃O₂^- has to be equal to the concentration of H₃O⁺, since each molecule of acid that dissociates generates one of each. This means that the concentrations of C₂H₃O₂^- are the same as those of H₃O⁺ in all cases.

Also, since each H₃O⁺ (and C₂H₃O₂^-) was generated form a HC₂H₃O₂, the concentration of this last is difference between the original concentration and the concentration that dissociated. This is:

$[HC_{2}H_{3}O_{2}]=[HC_{2}H_{3}O_{2}]_{initial}-\left [H_{3}O^{+} \right ]$

Since the initial concentration of the acid is not shown in your pictures, I cannot calculated, but it should be fairly simple to do it on your own! If not, please write them in the comments sections and I'll help you out.