Expt. 2 Preparation and Standardization of Solutions for Acidimetry and Alkalimetry

DATA SHEET

A. Standardization of prepared NaOH solution

Data & Results: Complete the table.

	TRIAL 1	TRIAL 2	TRIAL 3
Wt. of KHP (MM 204 g/mol)	0.3580 g	0.3650	0.3600
Titration Data
Final Reading	7.50 mL	14.70 mL.	22.00 mL
Initial Reading	0.00 mL	7.50 mL	14.70 mL
Total vol. of NaOH used	________	_________	_______
Std. Concn . of NaOH, (N)	________	_________	_______
Ave. Std. Concn. of NaOH	________

B. Standardization of the prepared HCl solution

Data & Results: Complete the table.

	TRIAL 1	TRIAL 2	TRIAL 3
Vol. of HCl used	20.00 mL	20.00 mL	20.00 mL
Titration Data
Final Reading	19.00	18.80	19.20
Initial Reading	0.00 mL	0.00 mL	0.00 mL
Total vol. of NaOH used	_______	_______	_______
Std. Concn . of HCl (N)	_______	_______	_______
Ave. Std. Concn. of HCl	________

NOTE: All weight readings from analytical balance must be expressed up to 4 decimal places. All volume readings must be expressed up to 2 decimal places.

Guide Questions

1. Give the general directions for the use of volumetric flask in the preparation of accurate volume solution.

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2. Write the equation showing how to determine the calculated concentration of NaOH:

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of HCl: ________________________________________________________________________

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3. What is the appropriate indicator in the titration of a strong acid with a strong base? ____________________________ of a weak acid with a strong base? ______________________
4. How do you differentiate the method of standardizing the NaOH solution from that of HCl solution? _______________________________________________________________________

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5. What is a primary standard substance? _______________________________________________

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(this is only a guideline on how to compute)

GUIDELINES ON COMPUTATIONS NOTE: Review previous lesson on concentration units particularly Normality A. Standardization of NaOH solution (Sample Computation) Total Vol of NaOH used in the titration = Final Reading Initial Reading = (ex. 10.00 mL) Std. Concn (N) of NaOH. At equivalence pt. of titration, number of equivalence acid = number of equivalence base number of equivalence KHP = Noon Xhens Egut.KHP KHP Nof NaOH= g KHP 0.4580 g = 0.2206 eq./L ES WI. KHP x V NaOH 204g/eq x 0.01000 L Eg-wt. KHP (CH.COOK.COOH or potassium acid phthalate) with 1 replaceable H = 204 g/mol 1 eq/mol Ave. Std. Concn, NaOH = Sum of Normality for 3 trials 3 B. Standardization of HCI (Sample Computation) Total Vol of NaOH used in the titration = Final Reading Initial Reading = (ex. 19.50 mL) Std. Concn of HCL At equivalence pt. of titration, number of equivalence acid = number of equivalence base No X Vacid = Nuke x Mase Nacid - Nu XV Vicid N of HC1 NNaOH x VNaOH = 0.2206 N , 19.50 mL 0.2151 N V HCI 20.00 mL NOTE: For computation of Std concn of HCl in each trial, used Ave. Std. Concn of NaOH. Ave. Std. Concn, HCI = Sum of Normality for 3 trials 3 NOTE: Ave. Std. Concn, NaOH & Ave Std. Concn, HC1 will be used in the next experiments' calculations