Question

Pre-laboratory Assignment Name: Read the experiment and answer the following questions as directed by your instructor. 1. In this experiment, you will use potassium hydrogen phthalate (abbreviation KHP, formula HKCH.0) to standardize (to determine the concentration precisely of) the NaOH solution. What is the molar mass of KHP? 2. In Part 1, you will titrate a weighed mass of KHP (dissolved in water) with the unknown NaOH solution. What data must you collect in order to find [NaOH)? List the headings you would use in a table to record this data. 3. Write the products of the reaction between the acid KHP and the base NaOH, and balance the reaction: HKC,H,O4(s) + NaOH(aq) → 4. Assume the [NaOH) = 0.150 M: a. If 12.0 mL NaOH is used in the titration, how many moles OH' would this represent? b. How many moles of KHP would be required to react with this amount of NaOH? C. What mass of KHP would be needed to give this number of moles? 5. Once you have determined (NaOH), you will use the base to titrate an unknown weak acid. You will be using LoggerPro to collect pH vs. volume NaOH data. Read the relevant section(s) of your text, and sketch below what you would expect to see for (a) a strong acid being titrated with NaOH (b) a weak acid being titrated with NaOH. 6. Look at Equation (6), the Henderson-Hasselbalch equation. Under what conditions will pH - pk.?

Answer 1

For the titration of KHP and NaOH all the necessary details are attached in the answersheet .

Attached Answer Sheets -
sol" 1) Molas Mass of KHP - HKC 8 H 404 It would be the sum of atomic weights of all the elements present in KHP. Lets, do this element wire- Element Atomic weight (g) 12 16 ox 39 Molar Mass of HK C&H 404 = H K Ce H4 04 1 + 39 + 8x12 + 4x1 + 4x16 = 1+39 + 96+ 4 + 64 = 204 g/mole Thus, the molar mass of kHP is 204 glmole. Sol" 2) Data to be collected in order to find NaOH- i) volume of Known KHP required to reach equivalance / end point or color change. In this titration NaOH is being added from burette to known solution of KHP in flask. RECORD IRUN Initial Burette Reading (NaOH) TABLE Final Busette Readi (NaOH) color a Point I dm

Sol 3) Product of reaction between the acid Kup and base NaOH - H K Cg H4 04 (s) + NaOH(aq) → Co Huo uk Nat HO H20 Sol 4) a ] Given NaOH concentration = 0.150N. Volume of NaOH = 12ml or 12 x 103 l. Molar Mass of NaOH will be the sum of molar mass of each element in NaOH. so Na o H 23+ 16 + 7 = 40 g. . I mole of NaOH = 40 g NaOH. Molarity is given by - Moles of solute (NaOH) Litres of solution → 0.150 = Moles of solute 12x 10-3 or moles of solute = 0.150 X 12 X 103 : 1.8x10² moles of Naoh will have 1.8x10 3 moles = 118 x 10-3 moles. of oth because NaOH Nat + oH I mole Imole mole

4 b) According to chemistry of Reaction Imole of KHP completely reacts with I mole of NaOH Thus, 118 x 103 moles of KHP is required for the reaction of giren Naoh solution. Mass of KHP would be. olar Mass of KHP = 204 g or 1 mole of KHP = 204g. Thus, 1.8 x 103 moles of kHP = 20481.8x 10 g = 0.3672 g of KHP. Thus 0.3 672 g of KHP is needed.