Is Dissolving Sugar in Water a Physical or Chemical Reaction?

The act of sugar dissolving in water is a physical change. Physical change is defined as when a substance changes form without changing chemical structure, and chemical change is defined as the change in chemical bonds.

The Confusing Part

The confusing part is due to that fact that sugar dissolving in water is forming hydrogen bonds between the water and sucrose molecules. While this is a intermolecular bond, it is not a breaking or forming of a chemical bond.

Examples of Physical Changes

Example of physical changes are water boiling from liquid into vapor form, and water freezing from liquid into solid form.

Example of Chemical Changes

Examples of chemical change are combustion and respiration. Whenever atoms bond to each other differently through either breaking, forming, or breaking/forming chemical bonds this is a chemical change. If just the physical form is changed, then this is a physical change.

The Reverse is True

The reverse of a chemical reaction is always another chemical reaction, and the reverse of a physical reaction is always a physical reaction. The opposite of respiration is photosynthesis and the opposite of freezing is melting.

Nuclear Reactions

The reaction of Fusion and Fission are defined as neither physical or chemical changes, they are the breaking and forming of internuclear forces, not chemical or intermolecular bonds.