e.g. Melt water or dissolving street in water
Chemical reactions space the processes through which chemicals connect to type new chemicals with different compositions. (source)
e.g. Burn $ceH2$ come $ceH2O$
But what is dissolving salt in water? Is the a physical change (like dissolve sugar) or is that a chrischona2015.org reaction?
I would think the dissolving a non-reactive salt, prefer $ceNaCl$ in water have the right to be thought about as a physical change. This is because, you can recover the salt by evaporating the water away.
From the Wikipedia page of physical change
In general a physical adjust is reversible making use of physical means. For example, salt liquified in water can be recovered by enabling the water come evaporate.
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But the distinction between physical and also chemical adjust can be misleading and also confusing in ~ times. In general, anything the does not adjust the chemical constitution of the substance, is a physics change.
When friend dissolve $ceNH3$ in water, the following equilibrium is set up:
$$ceNH3 + H2O NH4+ + OH-$$
But if you warmth the water up, you will get ago the original ammonia without any type of chemical change in that composition. However, the ammonia does readjust its chrischona2015.org composition in water, together $ceNH4+$ ions are formed. By that argument, you have the right to say that the dissolved of an ionizable salt is a chrischona2015.org change.
In part cases, dissolved of a compound have the right to be referred to as a true chrischona2015.org reaction. Because that example, when you dissolve Calcium oxide ($ceCaO$) in water, a vigorous chemical reaction bring away place, forming $ceCa(OH)2$. You can not get ago the original $ceCaO$ by just evaporating the water. In situation of aqueous equipment of $ceAlCl3$, if you try to evaporate the water by heater the solution, you will get ago only $ceAl(OH)3$ together anhydrous $ceAlCl3$ reacts v water as quickly as that is in call with water, to kind $ceAl
What i am trying to say is that some transforms can be classified into one of these types, while part other changes can not be given a clear classification. Melt of water is plainly a physical change, if reaction that $ceH2$ and also $ceO2$ is clearly a chemical change. One another fact, putting repaint on a canvas is not always a physics change. In truth some paints are manufactured in such a way that during drying, part chemical reaction occur, because of which the paint fixes firmly on the surface. This is the reason numerous water thinnable paints deserve to not be liquified in water when they come to be dry.
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To conclude, you must not hold difficult classifications like that in your mind. However, my final verdict: dissolve a salt is physical adjust (mostly).