Is coloring a paper a chemical change?

Answer 1

Answer

I would say yes... in some way chemistry is like microcosmical Physics... if a substance absorbes light in a wavelength the eye can detect (ca. 400 nm to 800 nm), this absorbed wavelength can be transformed to its colour in the color-spectrum... so this color is absorbed... that means our eyes see the complementary color to that absorbed color (according to the color-circle of Johannes Itten).

I.e. the absorbed color is violet... then our eyes see yellow (the complementary color to violet). Or if green is absorbed... you should see red.

If you now have a chemical substance... that suddenly changes color... something about its chemical structure has changed. I would say not the color change is a chemical property, but the color itself that the specific substances have; that is a chemical property (the one of absorption of the complementary color).

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While true, the above is not the whole answer.

However, there are some instances where it is a physical property. A film of petrol (gasoline) on water, or the skin of a soap bubble will change colour - not because of any chemical changes - but because of changes in the thickness of the film affect its optical properties. A purely physical change.

The heat radiated by objects depends on their temperature. For example a piece of iron can be heated until it glows red but chemically it is not altered.

Answer 2

Yes.

The signs of a chemical change are:

- Change in smell

- Sounds

- Change in color

- production of gas

- change in temperature

Answer 3

No not chemical. It is a change to the sheet of paper, but the paper is still 'white' underneath the ink or paint (unless it soaks in - then it's a mixture?)

Answer 4

no it is not