Is putting mentos in coke a physical or chemical change?

When Mentos are dropped into Diet Coke, the candy's gelatin coating creates nucleation sites for carbon dioxide gas bubbles to form. This is because the surface of the Mentos is covered in tiny pores, which provide nucleation sites for the dissolved carbon dioxide in the soda to form bubbles. As the bubbles grow, they rise to the surface of the liquid, creating the characteristic eruption of Diet Coke. The reaction between Mentos and Diet Coke is an example of a physical change because the chemical composition of the substances does not change. The Mentos simply provide a surface for the carbon dioxide to bubble up.