Is Dissolving Salt in Water a Chemical Change or Physical Change?

Salt in Water - Type of Change

Dissolving salt in water
Who would think dissolving salt in water could be so complicated? There are valid arguments for calling it either a chemical change or physical change. Neustockimages / Getty Images

When you dissolve table salt (sodium chloride or NaCl) in water, are you producing a chemical change or a physical change? A physical change results in a change of the material's appearance, but no new chemical products result. A chemical change involves a chemical reaction, with new substances produced as a result of the change.

Why Dissolving Salt Would Be a Chemical Change

When you dissolve salt in water the sodium chloride dissociates in Na+ ions and Cl- ions, which may be written as a chemical equation:

NaCl(s) → Na+(aq) + Cl-(aq)

Therefore, dissolving salt in water is an example of a chemical change. The reactant (sodium chloride or NaCl) is different from the products (sodium cation and chlorine anion). Thus, any ionic compound that is soluble in water would experience a chemical change. In contrast, dissolving a covalent compound like sugar does not result in a chemical reaction. When sugar is dissolved, the molecules disperse throughout the water, but they don't change their chemical identity.

Why Some People Consider Dissolving Salt a Physical Change

If you search online for the answer to this question, you'll see about equal numbers of responses arguing that dissolving salt is a physical change as opposed to a chemical change. The confusion arises because one common test to help distinguish chemical and physical changes is whether or not the starting material in the change may be recovered using only physical processes.

If you boil the water off of a salt solution, you'll obtain salt.

So, you've read the rationale. What do you think? Would you agree dissolving salt in water is a chemical change?

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