Question

Tooth enamel ( Ca5(PO4)3(OH) ) reacts with acid according to the reaction below: Ca_5(PO_4)_3(OH) (s) + H^+(aq) \leftrightarrow 5Ca^{2+}(aq) + 3HPO_4^{2-}(aq) + OH^-(aq) C a 5 ( P O 4 ) 3 ( O H ) ( s ) + H + ( a q ) ↔ 5 C a 2 + ( a q ) + 3 H P O 4 2 − ( a q ) + O H − ( a q ) What happens if we add more acid?

Answer 1

Answer: The tooth enamel will dissociate more in the presence of acid.

Explanation:

The chemical formula for tooth enamel is $Ca_5(PO_4)_3(OH)$

The chemical reaction of this in the presence of acid follows:

$Ca_5(PO_4)_3(OH)(s)+H^+(aq.)\leftrightarrow 5Ca^{2+}(aq.)+3HPO_4^{2-}(aq.)+OH^-(aq.)$

When more acid is added, acid will dissociate into hydrogen ions and more number of $H^+$ ions will be added on the reactant side.

So, according to Le-Chateliers principle, if there is any change in the variables of the reaction, the equilibrium will shift in the direction in order to minimize the effect.

In the given equilibrium reaction, hydrogen ion is getting increased on the reactant side, so the equilibrium will shift in the direction to minimize this effect, which is in the forward direction.

Thus, the tooth enamel will dissociate more in the presence of acid.