Question

Calculate the theoretical molecular weight of your unknown acid if it had four reactive protons and reacted with the same amount of NaOH as you measured in this experiment.

Number of protons available for reaction with OH-

trial 1: 2

trial 2: 2

trial 3: 2

Volume of NaOH solution used (mL)

trial 1: 21.59

trial 2: 21.32

trial 3: 20.51

Molarity of NaOH solution (M)

trial 1: 0.138

trial 2: 0.136

trial 3: 0.146

Average Molarity of NaOH: 0.14M

Mass of unknown acid used for titration (g)

trial 1: 0.25

trial 2: 0.25

trial 3: 0.25

Volume of NaOH solution used (mL)

trial 1: 30.31

trial 2: 30.06

trial 3: 32.3

Moles of unknown acid (mol)

trial 1: 0.00212

trial 2: 0.00210

trial 3: 0.00226

Molecular weight of unknown acid (g/mol)

trial 1: 117.92

trial 2: 119.04

trial 3: 110.61

Answer 1

Page No. Date A diprotic Acid Solution :- In the Given experiment is used. Then, the equation will be H₂ A + 2NaOH2 H o+ Na, A We have to calculate the molar mans of Tetraprotic Acid Hy A + 4 NaOH + H₂O + Nay A Now, for this Imole of Acid u mole of base is required. According to Given experiment moles of Nootused - molarity & volume I used = 0-14% Vote molerity x volumelwed molarity of NaOH (liven) = 0.14m Average volume of NaOH = 30.39 + 30.06 +32 ] 3 a 30-89 mL

Page No. Date 1 moles of NaOH used = 0.14 X 30.89 - 4:32.5mmok Thon, moles of Arid = 4.325 = 1.0 Samole. = 1:08 millimoles Now, According to the definition of moes moles - mass of Acid mol.wt. f Acid Mass of Acid mol wt of Acid 108 - mass of unknown acid = 0.25 g Then, mol wt. f Aid = 0.25 I milli - 10-3 1.08 milli moles mol wt of Acid = 0.25 te8 x 103 = 331.48 9 molecular wat of Acid = 231.48 g