If you detect a change in the color of the material why does this indicate that a chemical reaction might have occurred?

Answer 1

Yes

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This is not a mandatory indicator.

Answer 2

The properties of a substance which determine its color are chemical properties (the color is determined by the optical properties which are largely determined by the bonding interactions). Therefore a change in color is indicative of a change in bonding, which is a chemical change.

Answer 3

Color change indicates either a physical change or a chemical change. The physical change would be the two or more substances mixing together and changing the color due to the different colors of the substances. However, color change could also mean that the compounds or elements formed a totally new compound/elements, showing a chemical change.

Answer 4

Materials absorb energy from outside in the form of electromagnetic waves. Energy is absorbed by the chemical bonds in molecules (or electron orbitals in atom).

As you can see colour changes with wavelength, now different type of chemicals absorbs different wavelength of electromagnetic waves (it depends on the shape and size of the bond or orbit).

Now lets take KMnO4; its colour is violet because this molecule absorbs mostly light which has wavelength from 490 nm and 540 nm so it absorbs cyan and green colour. But it does not absorb violet nor other colours so much. That means that this molecule reflects it, that's why we see it as violet, it reflects that colour back to us.

So different chemical absorb or reflect different colour of light, that why they gain colour. Now if chemical changes its structure, it changes its bonds in molecule, and different bonds absorb different light, that's why chemicals may change colour after reaction.

Answer 5

it counts as a physical change because.. for example: if your face is bright red, it could mean u have a fever. and if u have a fever u will have some physical weakness. everything is connected basically.

Answer 6

It shows that the reactants (whatever the reaction starts with) are combining/reacting and turning into products (the end substance). Stable molecules will have a specific color and will not change color unless it reacts with something else.

Answer 7

It indicates that a chemical reaction occurred because 2 different chemicals combine in a material changing it's color as the reaction.

Answer 8

A color change can be an indication for the formation of a new compound.