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Direct Titration 1

This document contains three examples of titration problems involving the titration of a primary standard with a sodium hydroxide or hydrochloric acid solution of unknown concentration. The first example involves titrating potassium hydrogen phthalate with sodium hydroxide to determine the molarity of the sodium hydroxide solution. The second example involves titrating sodium carbonate with hydrochloric acid to determine the molarity of the hydrochloric acid solution. The third example involves titrating a sample containing oxalic acid with a sodium hydroxide solution of known molarity to determine the percentage of oxalic acid in the sample.

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160 views3 pages

Direct Titration 1

This document contains three examples of titration problems involving the titration of a primary standard with a sodium hydroxide or hydrochloric acid solution of unknown concentration. The first example involves titrating potassium hydrogen phthalate with sodium hydroxide to determine the molarity of the sodium hydroxide solution. The second example involves titrating sodium carbonate with hydrochloric acid to determine the molarity of the hydrochloric acid solution. The third example involves titrating a sample containing oxalic acid with a sodium hydroxide solution of known molarity to determine the percentage of oxalic acid in the sample.

Uploaded by

parisdelapena
Copyright
© © All Rights Reserved
We take content rights seriously. If you suspect this is your content, claim it here.
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Download as PDF, TXT or read online on Scribd
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KEMANA1 DEPARTMENT OF CHEMISTRY

[SEATWORK] SW3: DIRECT TIRATION METHOD

____________________________________________________ SCORE: ______________


(PRINT Family Name, Given Name) 40

Example 1: Potassium hydrogen phthalate, KHC8H4O4 (MM = 204.23), is a primary standard acid
that reacts with sodium hydroxide on a 1:1 molar basis. Results showed that 0.5893 g of primary
standard grade potassium hydrogen phthalate required 22.49 mL of the titrant solution to reach the
phenolphthalein end point. Calculate the molar concentration of the NaOH solution.
KHC8H4O4 + NaOH ¾® NaKC8H4O4 + H2O
Preliminary Questions
Check the box that describes the sample problem for titrimetric analysis (1 pt each)
Standardization of a Titrant Solution Analysis of a Sample

What are you looking for in the problem?


%(w/w) NaOH Molarity of NaOH

Identify the titrant solution Identify the primary standard acid

KHC8H4O4 KHC8H4O4

NaOH NaOH

NaKC8H4O4 NaKC8H4O4

What is the analyte? What is the source of the analyte?

KHC8H4O4 Impure sample


Highly pure primary standard grade
NaOH
reagent
NaKC8H4O4 solvent
Calculate the molar concentration of the NaOH solution.
Show the complete solution (include all units of measurement and the required conversion factors) to each of
the following problems. Enclose the final numerical answer (round-off the final answer to the correct number of
significant figures) in a box.
Write the stoichiometric mole relationship between the reactants (2 pts)

_____ mole KHC8H4O4 = _____ mole NaOH


Express the stoichiometric mole relationship between the reactants in the form of a ratio (2 pts each)
KEMANA1 DEPARTMENT OF CHEMISTRY

Calculate the molar concentration of the NaOH solution.


Write the mathematical equation for MOLARITY (include the required set of units) (2 pts)

STEP 1. Calculate the amount (moles) NaOH. (4 pts)

STEP 2. Calculate the MOLARITY of the NaOH solution. (4 pts)

Example 2: Sodium carbonate, Na2CO3(MM = 105.99) is a primary standard base that reacts with HCl as
follows
Na2CO3 + 2HCl ¾® 2NaCl + CO2 + H2O
If 40.37 mL of HCl(aq) were required to titrate a solution containing 221.4 mg of primary standard, Na2CO3,
calculate the molarity of the HCl solution.
Preliminary Questions
Check the box that describes the sample problem for titrimetric analysis (1 pt)
Standardization of a Titrant Solution Analysis of a Sample

What are you looking for in the problem? Check the box that answers the question. (1 pt)
%(w/w) HCl Molarity of HCl
Calculate the molar concentration of the HCl solution.
(6 pts)
KEMANA1 DEPARTMENT OF CHEMISTRY

Example 3: A 0.5537 g sample containing oxalic acid required 21.62 mL of 0.09377 M NaOH for titration.
Calculate the % H2C2O4 (MM = 90.04) present in the sample.
H2C2O4 + 2NaOH ¾® Na2C2O4 + 2H2O
Preliminary Questions
Check the box that describes the sample problem for titrimetric analysis(1 pt)
Standardization of a Titrant Solution Analysis of a Sample

What are you looking for in the problem? Check the box that answers the question. (1 pt)
%(w/w) H2C2O4 Molarity of H2C2O4

Identify the titrant solution Identify the analyte

H2C2O4 H2C2O4

NaOH NaOH

Na2C2O4 Na2C2O4

Calculate the % H2C2O4 (MM = 90.04) present in the sample..


Show the complete solution (include all units of measurement and the required conversion factors) to each of
the following problems. Enclose the final numerical answer (round-off the final answer to the correct number of
significant figures) in a box. (6 PTS)

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