Question

Acid / Base Titrations: Pre-Laboratory Assignment 1. Give at least two characteristics desirable in a primary standard. 2. Define equivalence point and bitration end point. Do these two points in a titration occur when the same volume of titrant has been added? Explain. 3. A student standardized a NaOH solution using KHC.H.O.. Three different KHC.H.O. samples were dissolved in water and titrated with the same NaOH solution, each to a phenolphthalein end point. The pertinent reaction is: KHC3H404(aq) + NaOH( g) + NaKCH404(aq) + H20(4) Results from these three runs are summarized in the data table below. Complete the following summary table of calculated values using the given experimental measurements. Mass of KHC8H40, titrated, g 0.452 0.470 0.442 Volume of NaOH(aq) required, mL 15.45 15.99 15.05 Number of moles of KHC8H4Otitrated, mol Number of moles of NaOH required, mol Volume of NaOH solution required, L Molarity of NaOH solution, mol/L Mean molarity of NaOH solution, mol/L Show clear work for the following: a) Moles of KHC8H.O titrated for Run #1 b) Moles of NaOH required for Run #1 c) Molarity of NaOH as determined by Run #1 Acid Base Titr

Answer 1

neutralize the charactertie primary standard ave. I should be a low reactivity y should be of High purity. ② 6 Equivalence Point - The be the equivalence point. The boint at which moles & bare is equivalent to moles of acid or it is the point where the amount of titront point where added is sufficient enough to completely neutralize the qualyle solution.. Tibaliou end fourt - It is the point which tells us that the indicator changes colour. It is the point which tells that equivalence the fourt where beght has been reached. It is a lot futher titraut could be added. mare of KH G H y Oq & moles could be found out of debeat e ir molar mans KHCO Hy 04 Mo. of moles of Maol required = no. of moles of KHCg H407 malalay any of MaoH fould be found out by Mi Vibraon (M. Va engren {valence of Nash convertime into L} MNaOH = (M2 V₃ KM CH 404 M) Nach clear work (9) Moles & KH C8H404 = mars of KMC8H404 - Molar mars of KH C3 H404 (b) males of Naoh requised - Moles of KHC 8H404 ces molarity of MaOH = Moles of Madh A vol of Maot (in L) (1) a) ? MOOH + com 3 Na coz + 420 (6) MooH is deliquescent au nature and absorbs moisture some from ais. This affects the concentration the final solution has already been neutralised and it is nou urelers and hence discarded. 3. 3. moles of citric acid = moles of clinic acid mass of citric acid molartian e citric acid mars percent of citric acid = mail of citric acid litrated x 100 Total mars of citric acid in sample mean mars % f citric acid = mean mans & citric acid Total mais of citric acid in sample x100