Câu 18:

`a,`

Có: `KLPT(K_2(SO_4)_x) = 2 * KLNT(K) + x * ( KLNT(S) + 4 * KLNT(O) ) = 174` amu

`=>` `2 * 39 + x * ( 32 + 4 * 16 ) = 174` amu

`=>` `78 + x * 96 = 174` 

`=>` `x = 1`

`=>` CTHH: `K_2SO_4`

`b,`

Có: `KLPT(Ca_x(PO_4)_2) = x * KLNT(Ca)+ 2 * ( KLNT(P) + 4 * KLNT(O) ) = 310`

`=>` `40x + 2 * ( 31 + 4 * 16 ) = 310` amu

`=>` `40x + 190 = 310` amu

`=>` `x = 2`

`=>` CTHH: `Ca_2(PO_4)_3`