12 Questions
What is the main purpose of using an indicator in an acid-base titration?
To estimate the concentration of the acid or base in the sample.
Why is it important to repeat the acid-base titration experiment three times?
To ensure accuracy and reliability of the results.
What happens when a strong acid reacts with a strong base?
The pH of the solution remains constant.
Why is it necessary to standardize the NaOH solution by titrating it with HCl?
To find out the exact normality of NaOH.
Which type of glassware is NOT mentioned as necessary for an acid-base titration experiment?
Thermometer
What does it mean when it is stated that 'Strong acids and strong bases dissociate completely in water'?
They ionize fully into ions in water.
What is the purpose of titration in chemistry?
To determine the volume of a solution needed to react with another solution
What is the primary purpose of using an indicator in a titration process?
To detect the completion point of the titration
In titration, what is a primary standard solution known for?
Being highly pure and stable
What defines the equivalence point in a titration?
The theoretical point where two reactants are just equivalent
What distinguishes secondary standard solutions from primary standard solutions?
Secondary solutions are easier to weigh
Why is an indicator used in titration?
To assist in detecting the end point of the titration
Study Notes
Titration
- Titration is a technique used to determine the concentration of a solution by measuring the volume of another solution needed to completely react with it.
Principles of Titration
- Based on the complete chemical reaction between the analyte and the reagent (titrant) of known concentration.
- Analyte: a solution of unknown concentration but known volume in a conical flask.
- Titrant: a solution of known concentration in a burette.
Standard Solutions
- Primary standard solution: extremely pure, highly stable, and can be weighed easily.
- Secondary standard solution: less pure, less stable, and cannot be weighed easily.
Titration Process
- Equivalence point: the theoretical point where the amounts of two reactants are just equivalent.
- End point: the practical point at which the reaction is observed to be complete, usually detected with an indicator.
- Indicator: an auxiliary substance that helps detect the completion of the titration process at the end point.
Acid-Base Titration
- Involves a sample of unknown concentration of acid estimated with a known concentrated base or vice versa.
- Strong acids and strong bases dissociate completely in water.
- Example: determination of the normality of sodium hydroxide solution by a standard solution of hydrochloric acid.
Equipment and Materials
- Glassware: burette, stand, conical flask, funnel, beaker, pipette, graduated cylinder, dropper, and washing bottle.
- Materials: HCl solution (standard), NaOH solution (unknown normality), and phenol naphthalene indicator.
Procedure
- Transfer 5 ml of unknown NaOH solution to a conical flask.
- Add 2-3 drops of phenol naphthalene indicator.
- Fill the burette with HCl solution to the zero mark.
- Titrate NaOH against HCl until the color changes from colorless to pink.
- Repeat the experiment three times and record the results.
Calculations
- Calculate the average volume of HCl used.
- Calculate the unknown concentration of NaOH using the average volume of HCl used.
Learn about the technique of titration in chemistry where the concentration of a solution is determined by measuring the volume needed to react with another solution. Understand the principle of titration based on chemical reactions between the analyte and titrant of known concentration.
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