To Identify Acidic Radical Present In Given Sample Of Salt (s4). | Grade Xi
0APPARATUS REQUIRED
- Test tube
- Test tube stand
- Dropper
- Splinter
- Spirit lamp
- pH paper
CHEMICALS REQUIRED (if necessary)
- Sample of salt (S4)
- Dilute hydrochloric acid (HCl)
- Dilute sulfuric acid (H2SO4)
- Dilute nitric acid (HNO3)
- Sodium hydroxide (NaOH) solution
- Barium chloride (BaCl2) solution
- Silver nitrate (AgNO3) solution
THEORY
Acids are substances that donate protons (H+ ions) in a chemical reaction. They have a sour taste, react with metals to produce hydrogen gas, and turn blue litmus paper red.
The acidic radical of a salt is the negative ion that is formed when the salt is dissolved in water. The acidic radical of a salt can be identified by performing a series of chemical tests.
PROCESS
- Take a small sample of the salt (S4) and dissolve it in a test tube containing a small amount of water.
- Test the pH of the solution using pH paper. If the pH is less than 7, then the salt is acidic.
- Add a few drops of dilute hydrochloric acid (HCl) to the solution. If the solution effervesces (bubbles), then the acidic radical of the salt is carbonate (CO32-).
- Add a few drops of dilute sulfuric acid (H2SO4) to the solution. If the solution effervesces, then the acidic radical of the salt is sulfate (SO42-).
- Add a few drops of dilute nitric acid (HNO3) to the solution. If the solution effervesces, then the acidic radical of the salt is nitrate (NO3-).
- Add a few drops of sodium hydroxide (NaOH) solution to the solution. If the solution turns cloudy, then the acidic radical of the salt is phosphate (PO43-).
- Add a few drops of barium chloride (BaCl2) solution to the solution. If a white precipitate forms, then the acidic radical of the salt is sulfate (SO42-).
- Add a few drops of silver nitrate (AgNO3) solution to the solution. If a white precipitate forms, then the acidic radical of the salt is chloride (Cl-).
OBSERVATIONS
The observations made during the experiment are listed in the following table:
| Test | Observation | Conclusion |
|---|---|---|
| pH test | pH < 7 | The salt is acidic. |
| HCl test | Effervescence | The acidic radical of the salt is carbonate (CO32-). |
| H2SO4 test | Effervescence | The acidic radical of the salt is sulfate (SO42-). |
| HNO3 test | Effervescence | The acidic radical of the salt is nitrate (NO3-). |
| NaOH test | Cloudiness | The acidic radical of the salt is phosphate (PO43-). |
| BaCl2 test | White precipitate | The acidic radical of the salt is sulfate (SO42-). |
| AgNO3 test | White precipitate | The acidic radical of the salt is chloride (Cl-). |
CALCULATION
The calculation of the concentration of the acidic radical in the salt (S4) can be done using the following formula:
Concentration of acidic radical = (Weight of acidic radical / Molecular weight of acidic radical) x 100
RESULTS
The results of the experiment show that the acidic radical present in the given sample of salt (S4) is sulfate (SO42-).
PRECAUTIONS
- Always wear gloves and safety goggles when conducting chemical experiments.
- Handle acids and bases with care.
- Do not heat chemicals in a closed container.
- Do not dispose of chemicals in the sink.