The enamel present on teeth becomes much hard | vedclass

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Question

(A) The enamel on teeth is composed of hydroxyapatite,which is represented as $3 Ca_3(PO_4)_2 \cdot Ca(OH)_2$.When fluoride ions $(F^-)$ are present i

Vedclass · Accepted Answer

$X = Ca(OH)_2, Y = CaF_2$

Vedclass · Answer

(A) The enamel on teeth is composed of hydroxyapatite,which is represented as $3 Ca_3(PO_4)_2 \cdot Ca(OH)_2$.When fluoride ions $(F^-)$ are present in water or toothpaste,they react with the hydroxyapatite to form fluorapatite,which is much harder and more resistant to acid decay.The chemical reaction is: $3 Ca_3(PO_4)_2 \cdot Ca(OH)_2 + 2 F^- \rightarrow 3 Ca_3(PO_4)_2 \cdot CaF_2 + 2 OH^-$.Comparing this to the given formula,we identify $X = Ca(OH)_2$ and $Y = CaF_2$.

The enamel present on teeth becomes much harder due to the conversion of $[3 Ca_3(PO_4)_2, X]$ into $[3 Ca_3(PO_4)_2, Y]$. What are $X$ and $Y$?

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