the goal:

Explanation of how we can infer a chemical change has occurred.

Materials and tools:

Ammonia solution - Distilled water - Glass beaker - Universal indicator - Effervescent tablets.

Steps:

1- Put a quantity of distilled water in the glass.

2- Add drops of ammonia solution into the water in the glass, and observe what happens.

3- Put drops of universal indicator into the solution and observe the color that forms.

4- Add an effervescent tablet to the solution and observe what happens.

Note:

We observe a color change from blue to orange, and we notice the formation of foam from the effervescent tablet, indicating the presence of gas.

Conclusion:

We can observe chemical changes through a change in color, the occurrence of a reaction or fizzing, or a change in temperature.

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You can read more about how a chemical change can be observed here.