3 Explain how the following sources of error would impact yo

3. Explain how the following sources of error would impact your calculated value of Ke, would it make the value lower, higher, or not affect it in any way? Explain. In the titration of acetic acid during the first week (initial concentration acetic acid), some water was left in the buret containing NaOH, diluting it. In the second week, the titration was conducted correctly a. b. Before the titration during the second week, some water was accidentally added to the reaction flask containing the equilibrium mixture. 13 CHE-1261 Experiment 5

Solution

a) The reaction between acetic acid (CH₃COOH) and NaOH is given as below.

CH₃COOH (aq) + NaOH (aq) --------> CH₃COONa (aq) + H₂O (l)

As per the stoichiometric equation,

1 mole CH₃COOH = 1 mole NaOH

The reaction takes place on a 1:1 molar basis. Since the solution was diluted in the first week, the original concentration of the NaOH was lower than the stated concentration; hence, a higher volume of the dilute NaOH is required to neutralize the moles of acetic acid present in the solution. Since there is no change in the number of moles of acetic acid (from week 1 to week 2), hence, the dilution will not affect the value of K_c.

b) The equilibrium reaction is given as

CH₃COOH (aq) + H₂O (l) <=======> CH₃COO^- (aq) + H₃O⁺ (aq)

K_c = [CH₃COO^-][H₃O⁺]/[CH₃COOH] ……(1)

(the concentration of solid and liquid species do not appear in the expression for the equilibrium constant)

When the supplied acetic acid is diluted due to the addition of water, [CH₃COOH] is lower than that in (1) and hence, the calculated value of K_c will be high.