Which procedure could be used to demonstrate that matter is conserved during a chemical change or reaction

Answer 1

A classic procedure to demonstrate the conservation of matter during a chemical change is to conduct a closed-system chemical reaction in a controlled environment. Here's a step-by-step outline of a simple experiment that can illustrate this principle:

Materials Needed:

1. Two reactants that can react together (for example, baking soda and vinegar).
2. A balloon or a gas-tight container.
3. A balance to measure mass.
4. A graduated cylinder or measuring cup.
5. Safety goggles and gloves for safety.

Procedure:

1. Measurement of Initial Mass:

   • Weigh the empty container (if using one) and record its mass.
   • Measure a specific amount of baking soda and add it to the container.
   • Measure a specific amount of vinegar in a separate container and note its volume.
   • Weigh the container with baking soda and record this mass.

2. Set Up the Reaction:

   • Carefully pour the vinegar into the container with baking soda, or quickly add the vinegar to the container and seal it with a balloon or lid to ensure no gas escapes (this creates a closed system).
   • If using a balloon, it should inflate as the reaction proceeds due to the release of carbon dioxide gas.

3. Measure the Mass After Reaction:

   • After the reaction has visibly completed (when bubbling subsides), carefully weigh the entire setup again, ensuring that nothing has escaped from the system.

4. Calculating Total Mass:

   • Record the final mass of the container with the reactants after the reaction has completed.
   • If applicable, ensure you include the mass of the balloon in your measurements.

5. Data Analysis:

   • Compare the initial mass (mass of container + baking soda + vinegar) to the final mass (mass of the container with products).
   • The two measurements should be nearly equal, demonstrating that matter has been conserved during the reaction.

Conclusion:

Through this experiment, students can observe that despite the change in the appearance of the substances (gas evolution, bubbling, etc.), the total mass of the system remains constant, thus illustrating the law of conservation of mass during a chemical reaction.

Notes:

• Be sure to conduct the experiment in an appropriate environment and with necessary safety gear.
• This procedure works best if everything is contained so that no gases can escape during the reaction.