Titration Technique Definition and Concepts

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Questions and Answers

Which statement about acid-base indicators is correct?

Their ions have colors that are identical to the undissociated molecule.

They do not change color at the equivalence point of a titration.

They are weak organic acids or bases that slightly dissociate in aqueous solutions to form colored ions. (correct)

They are strong acids or bases that completely dissociate in aqueous solutions.

What is the purpose of a back titration technique?

To determine the concentration of a strong acid or base.

To resolve problems encountered in direct titrations, such as slow titrations. (correct)

To prepare a standardized solution for use in other titrations.

To determine the concentration of an indicator solution.

In a back titration, what is the role of the standardized NaOH solution?

It is the analyte of unknown concentration.

It is the indicator used to determine the end point.

It is the solution being analyzed for its ascorbic acid content.

It is the titrant of known concentration. (correct)

Which of the following is true about phenolphthalein as an indicator in acid-base titrations?

It is colorless in neutral solutions and pink in basic solutions. Signup and view all the answers

In the experiment for determining ascorbic acid in vitamin C tablets, what role does phenolphthalein play?

It is the indicator used to determine the end point. Signup and view all the answers

What is the significance of the equivalence point in an acid-base titration?

It is the point at which the moles of added titrant are stoichiometrically equal to the moles of analyte. Signup and view all the answers

In an acid-base titration, what is the primary purpose of the indicator?

To determine the equivalence point by undergoing a color change Signup and view all the answers

In the context of the back titration technique, what is the role of the standardized NaOH solution?

It serves as the titrant solution of known concentration Signup and view all the answers

Which of the following statements accurately describes the relationship between the end point and the equivalence point in an acid-base titration?

The end point is located very close to the equivalence point Signup and view all the answers

According to the Brønsted-Lowry theory, which of the following statements is true about weak acids and bases?

Weak acids and bases both partially dissociate in water Signup and view all the answers

In the experiment for determining ascorbic acid (Vitamin C) in tablets, what is the role of phenolphthalein as the indicator?

It turns pink in the presence of excess NaOH Signup and view all the answers

Which of the following statements accurately describes the role of the titrant in an acid-base titration?

The titrant is the solution of known concentration used to determine the unknown concentration Signup and view all the answers

In the context of acid-base titrations, what is the primary purpose of performing a back titration?

To resolve issues related to slow titration rates or interference from other substances Signup and view all the answers

According to the definition provided, which of the following statements accurately describes the analyte in an acid-base titration?

The analyte is the solution of unknown concentration being analyzed Signup and view all the answers

Which of the following statements accurately describes the role of a strong acid or base in an acid-base titration?

Strong acids and bases are used as titrants due to their complete dissociation in water Signup and view all the answers

In the context of acid-base indicators, what is the significance of the color change observed at the end point?

It indicates that the equivalence point has been reached Signup and view all the answers

Study Notes

Titration

A technique used to determine the concentration of an identified analyte by reacting it with a solution of known concentration (titrant)
Involves adding a solution of known concentration from a burette to a measured volume of analyte

Analyte and Titrant

Analyte: a solution of unknown concentration (known volume)
Titrant: a solution of known concentration (volume obtained by titration)

Equivalence Point and End Point

Equivalence point: the point at which the moles of added titrant are stoichiometrically equal to the moles of analyte
End point: signals the end of titration where the indicator gives an observable change, located very close to the equivalence point

Acid-Base Chemistry

Acid: a proton (H+) donor (Bronsted-Lowry definition)
Base: a proton (H+) acceptor (Bronsted-Lowry definition)
Strong acid/base: completely dissociates with water
Weak acid/base: partially dissociates with water

Acid-Base Indicators

Weak organic acids or bases that dissociate slightly in aqueous solutions to form ions
Indicators change colors because their ions have colors that are different from undissociated molecules
Example: phenolphthalein, a weak acid that is colorless in acidic and neutral solutions and pink in basic solutions

Acid-Base Titration

A procedure used in quantitative analysis to determine the concentration of either an acid or a base
Indicator should change sharply at the equivalence point
At the end point of titration, all acids and bases are neutralized, and the flask contains water and salt only

Back Titration

An alternative technique to direct titration designed to resolve some problems encountered in direct titration, such as slow titration
Titrant: standardized NaOH solution
Analyte: ascorbic acid (Vitamin C tablet samples)
Indicator: phenolphthalein

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Description

This quiz covers the definition and key concepts of titration technique, where a solution of known concentration is used to determine the concentration of an unknown analyte. It includes information on analyte, titrant, equivalence point, and end point.