Magic show or chemistry lab? Sometimes it’s hard to tell the difference!

Color change chemistry experiments are interesting, visually appealing, and illustrate a wide range of chemical processes.These chemical reactions often produce spectacular color changes that appear to happen just by magic , they are visible examples of chemical changes in matter. When two or more substances combine to react, they produce a different structure, which has a total different composition and color .

Sodium Hydroxide and Phenolphthalein

Phenolphthalein is an indicator ,a chemical which changes colour depending on whether it meets an acid or a base. It turns purple if it meets something basic, such as ammonia and it stays colourless if it meets an acid like vinegar or a neutral substance like water. Sodium hydroxide is a base, so when you add phenolphthalein, the solution turns pink.

The Blue Bottle Demonstration

The "blue bottle demonstration" involves a solution of glucose, sodium hydroxide, methylene blue and distilled water. It is a reversible redox reaction . It changes colour from colourless to blue due to the oxidization that the oxygen does , than back again by shaking the solution.


The Traffic Light Demonstration

the traffic light demonstration is a reversible oxidation-reduction reaction. It involves KOH dissolved in water, dextrose (glucose) , along with the indicator solution (indigo carmine added to a mixture of ethanol and water). Initially, the solution appears green. At an intermediate stage the solution becomes red then it fades to be yellow .When shaking the flask the green colour reappears ( shaking dissolve oxygen from the air into the solution provoking the formation of the oxidized form) and then fades to red, then yellow again.

Starch and Iodine Solutions

The starch test is a chemical reaction that determines whether starch amylose is present in a substance. Add Iodine-KI reagent to a solution or directly on a potato or other materials such as bread, crackers, or flour. A blue-black color results if starch is present. If starch mylase is not present, then the color will stay orange or yellow.


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