Chapter Name: Atoms And Molecules
Activity Name: Change in mass in Atoms And Molecules
The experiment aims to demonstrate the change in mass that occurs before and after a chemical reaction.
Two solutions, one containing lead nitrate and the other containing potassium iodide, are mixed in a conical flask. The weight of the flask and its contents is measured before and after the mixing process.
- Lead nitrate
- Potassium iodide
- Distilled water
- Conical flask (250ml)
- Test tube
- Spring balance
- Rubber cork
Step by Step Procedure:
- Dissolve approximately 2 grams of lead nitrate in 100 ml of distilled water to prepare a lead nitrate solution.
- Dissolve approximately 2 grams of potassium iodide in 100 ml of water to prepare a potassium iodide solution.
- Take 100ml of the lead nitrate solution in a 250ml conical flask.
- Take 4ml of the potassium iodide solution in a test tube.
- Hang the test tube carefully in the flask without mixing the solutions. Cover the flask with a rubber cork. (Refer to figure 1 for setup)
- Carefully weigh the flask with its contents using a spring balance.
- Tilt and swirl the flask to mix the two solutions (Refer to figure 2).
- Weigh the flask again using the same spring balance as shown in figure 3.
- Record your observations:
- Weight of flask and contents before mixing =
- Weight of flask and contents after mixing =
- The initial weight of the flask and its contents before mixing the solutions.
- The final weight of the flask and its contents after the chemical reaction occurs.
- Handle lead nitrate and potassium iodide with care, as they may be hazardous if mishandled.
- Ensure that the test tube is securely hung in the flask and properly covered with the rubber cork.
- Use a clean and dry spring balance for accurate weight measurements.
- Follow proper laboratory safety guidelines while conducting the experiment.
Lesson Learnt from Experiment:
The experiment helps in understanding the concept of conservation of mass during a chemical reaction. The total mass of the substances before the reaction is equal to the total mass after the reaction.