Physical changes are minimal to changes that result in a difference in display screen without changing the composition. (source)

e.g. Melting water or dissolving street in water

Chemical reactions space the processes whereby chemicals interact to kind new chemicals with various compositions. (source)

e.g. Burn $\\ceH2$ come $\\ceH2O$

But what is dissolve salt in water? Is the a physical change (like dissolve sugar) or is it a chemical reaction?


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I would certainly think the dissolving a non-reactive salt, choose $\\ceNaCl$ in water deserve to be considered as a physics change. This is because, you deserve to recover the salt through evaporating the water away.

From the Wikipedia page of physics change

In general a physical adjust is reversible utilizing physical means. For example, salt dissolved in water have the right to be recovered by permitting the water to evaporate.

You are watching: Dissolving salt in water chemical or physical

But the difference between physical and chemical adjust can it is in misleading and also confusing at times. In general, anything that does not readjust the chemical constitution of the substance, is a physics change.

When girlfriend dissolve $\\ceNH3$ in water, the following equilibrium is set up:

$$\\ceNH3 + H2O NH4+ + OH-$$

But if you heat the water up, you will certainly get ago the initial ammonia without any kind of chemical change in that composition. However, the ammonia does readjust its chemistry composition in water, together $\\ceNH4+$ ions room formed. By the argument, you deserve to say the the dissolved of an ionizable salt is a chemistry change.

In part cases, dissolution of a compound can be referred to as a true chemistry reaction. Because that example, as soon as you dissolve Calcium oxide ($\\ceCaO$) in water, a vigorous chemistry reaction takes place, forming $\\ceCa(OH)2$. You cannot get back the original $\\ceCaO$ by simply evaporating the water. In instance of aqueous systems of $\\ceAlCl3$, if you try to evaporate the water by heating the solution, you will certainly get back only $\\ceAl(OH)3$ as anhydrous $\\ceAlCl3$ reacts through water as quickly as the is in call with water, to type $\\ceAl6Cl3$.

What i am trying to say is the some alters can be classified into one of these types, while part other changes can not be provided a clean classification. Melt of water is plainly a physics change, if reaction the $\\ceH2$ and also $\\ceO2$ is clearly a chemical change. One another fact, putting paint on a canvas is not always a physics change. In truth some paints are manufactured in together a way that throughout drying, some chemical reactions occur, due to which the repaint fixes firmly on the surface. This is the reason plenty of water thinnable paints can not be dissolved in water once they become dry.

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To conclude, you should not hold hard classifications like that in your mind. However, my last verdict: dissolve a salt is physical readjust (mostly).