Chemical formula of HA is often written as Ca10(PO4)6(OH)2 to denote its crystal

Question

Chemical formula of HA is often written as Ca10(PO4)6(OH)2 to denote its crystal structure. In CHA carbonate ions can take places of both hydroxide (called A-type substitution) and phosphate (called B-type substitution) ions. In general, formula for the A-type CHA could be written as Ca10(PO4)6(OH)2-2x(CO3)x. In this case, one carbonate ion substitutes two hydroxyl groups in order to maintain charge neutrality, but occupies only one OH- position, leaving an empty space called vacancy (VOH) in the place of the second OH- group. The formula can be rewritten as Ca10(PO4)6(OH)2-2x(VOH)x(CO3)x. In a similar manner, write formula for B-type substituted CHA, specify where vacancies are forming.

Explanation / Answer

From the given data for the Ca10(PO4)6(OH)2

The fomula for the B-type substituted CHA could be written as,

Ca(10-x)/2.V(PO4)6-x(CO3)x(OH)2

The vacancy arises by Ca2+ shift and leaving an empty space.

Related Questions

Navigate

• Browse (All)
• Browse C
• Subjects

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.