Are there chemical changes in the Hydrologic Cycle?

• A. There are no chemical changes, only physical.
• B. It converts water to hydrogen and oxygen.
• C. It produces many new chemical compounds.
• D. It dehydrates water to form minerals.

Answer: (A)

The hydrologic cycle is defined by physical changes of water, not chemical reactions. Evaporation, condensation, freezing, melting, and precipitation involve changes of state and movement between air, land, and oceans, but the chemical formula of water remains H2O throughout these processes. That’s why the idea that there are no chemical changes, only physical ones, best describes the cycle.

Think of it this way: the cycle moves and transforms water by changing its phase and location, not by creating new substances. Splitting water into hydrogen and oxygen would be a chemical reaction (and isn’t part of the normal cycle). Likewise, forming new chemical compounds or minerals would involve chemical changes beyond the cycle’s standard processes of evaporation, condensation, and precipitation.