Why is grape juice turning to wine a chemical change?

Grape juice turning into wine is a chemical change for several reasons:

* New substances are formed: The most significant change is the conversion of sugar (glucose and fructose) in the grape juice into alcohol (ethanol) and carbon dioxide. This is a chemical reaction catalyzed by yeast. The original sugar molecules are broken down and rearranged, resulting in completely different molecules with different properties.

* Irreversible process: You can't easily reverse the process to get back to the original grape juice. You can't simply evaporate the alcohol to leave the sugar behind.

* Changes in properties: The resulting wine has drastically different properties than the starting grape juice. It has a different taste, color, smell, and alcohol content. These changes are a direct result of the chemical reactions that occur during fermentation.

In summary: The process of converting grape juice into wine involves the formation of new substances (alcohol and carbon dioxide) through a chemical reaction, making it an irreversible change with significant alterations in the properties of the substance.