Change in mass in Atoms And Molecules – Class 9 Science Experiment

Chapter Name: Atoms And Molecules

Activity Name: Change in mass in Atoms And Molecules

Activity Description:

Change in mass in Atoms And Molecules - Class 9 Science Experiment

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.

Required Items:

  • Lead nitrate
  • Potassium iodide
  • Distilled water
  • Conical flask (250ml)
  • Test tube
  • Spring balance
  • Stand
  • Rubber cork
  • Thread

Step by Step Procedure:

  1. Dissolve approximately 2 grams of lead nitrate in 100 ml of distilled water to prepare a lead nitrate solution.
  2. Dissolve approximately 2 grams of potassium iodide in 100 ml of water to prepare a potassium iodide solution.
  3. Take 100ml of the lead nitrate solution in a 250ml conical flask.
  4. Take 4ml of the potassium iodide solution in a test tube.
  5. 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)
  6. Carefully weigh the flask with its contents using a spring balance.
  7. Tilt and swirl the flask to mix the two solutions (Refer to figure 2).
  8. Weigh the flask again using the same spring balance as shown in figure 3.
  9. Record your observations:
    • Weight of flask and contents before mixing =
    • Weight of flask and contents after mixing =

Experiment Observations:

  • 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.

Science Experiment Kits for Kids

Photo Title Price Buy
Einstein Box Junior...image Einstein Box Junior Science Gift Set | 2-in-1 Set of My First Science Kit & Slime Kit for 4-6-8 Year Olds| Birthday Gift for Boys & Girls ₹1,199.00
ButterflyEdufields 20+ Science...image ButterflyEdufields 20+ Science Kit For Kids | STEM Projects birthday gift For Boys and Girls Ages 7-8-10-12 |DIY Educational & Learning Experiment Toys for 7 To 12 Year Olds | Build 20+ Motor Machines ₹1,699.00
The Little Ones...image The Little Ones Science Kit - Science experiment kit for kids 6-8-10-12 years old,educational learning toys,Best gift for boys&girls,chemistry kit,science project[Complete science kit- 100+experiment]
WitBlox AI Artificial...image WitBlox AI Artificial Intelligence Robotic Science Kit for 101+ Project 137 Part 8 Yrs+, Interlocking Bricks, Electronic Sensor & Circuits to create Logic 2 Free Live Classes Gift Toy for Boys & Girls ₹3,699.00
Avishkaar Robotics Advanced...image Avishkaar Robotics Advanced Kit|150-In-1 DIY Stem Metal Kit|Multicolor|150+ Parts|Learn Robotics|Coding & Mechanical Design|for Kids Aged 10-14|Made in India|Educational DIY Stem Kit|Made in India ₹10,399.00
My Science Lab...image My Science Lab Ultimate Science Experiment Kit for Kids Age 6-14 | STEM Toys | Physics Kit Set | Science & Fun 5-in-1 Projects | School Science Kit | Best Educational Birthday Gift Toys for Boys and Girls ₹1,199.00

Similar Posts

Leave a Reply

Your email address will not be published. Required fields are marked *