Is the weathering of alkali chemical or physical change?

Is the weathering of alkali chemical or physical change?

The chemical formula of alkali is Na2CO3•10H2O. After weathering, the water molecule is lost. Obviously, the chemical formula is changed, and new substances are formed, so it is chemical change.

Why weathering is a chemical change, Isn't weathering the loss of crystal water, and deliquescence is the formation of crystal water? Why are two opposite processes, one chemical and one physical Why weathering is a chemical change, Isn't weathering a loss of crystal water, and deliquescence a formation of crystal water? Why are two opposite processes, one chemical and one physical

Only chemical changes in weathering, the loss of crystal water is the formation of new substances.
There are two variations in deliquescence, depending on the material.
If hydrates are formed. For example, anhydrous copper sulfate forms copper sulfate pentahydrate during deliquescence.
However, the NaOH solution is only formed in the process of deliquescence.
Some textbooks may define tides as physical changes because they define the concept of tide.