A solution is prepared by adding 100mL of 1M HC2H3O2(g) to 100mL of 1 M NaC2H3O2(aq). The solution is stirred and its pH is measured to be 4.73. After 3 drops of 1M HCl are added to the solution, the pH of the solution is measured and is still 4.73. Which of the following equations represents the chemical reaction that accounts for the fact that acid was added but there was no detectable change in pH?
1) HC2H3O2(g) + NaC2H3O2(aq) → HC2H3O2(aq) + NaC2H3O2(g)
2) HC2H3O2(g) + HCl(aq) → HC2H3O2(aq) + HCl(g)
3) HC2H3O2(aq) + HCl(aq) → HC2H3O2(g) + HCl(g)
4) HC2H3O2(aq) + NaC2H3O2(aq) → HC2H3O2(aq) + NaC2H3O2(aq)