40 баллов! Ребят, прошу решить, причём расписав всё досконально.

2)

дано

V(PH3) = 28 L

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m(P) - ?

V(H2)-?

2P+3H2-->2PH3

n(PH3) = V(PH3) / Vm = 28 / 22.4 = 1.25 mol

2n(P) = 2n(PH3) = 1.25 mol

n(P) = 1.25 mol

M(P) = 31 g/mol

m(P) = n(P) * M(P) = 1.25 * 31 = 38.75 g = 39 г

3n(H2) = 2n(PH3)

n(H2) = 3*1.25 / 2  = 1.875 mol

V(H2) = n(H2) * Vm =1.875 * 22.4 = 42 L

ответ 39 г , 42 л

3)

дано

m(CaCL2) = 240 g

+Na3PO4

--------------------------

m(Ca3(PO4)2)-?

3CaCL2+2Na3PO4-->Ca3(PO4)2↓+6NaCL

M(CaCL2) = 111 g/mol

n(CaCL2) = m(CaCL2) / M(CaCL2) = 240 / 111 = 2.16 mol

3n(CaCL2) = n(Ca3(PO4)2)

n(Ca3(PO4)2) = 2.16 / 3 = 0.72 mol

M(Ca3(PO4)2) = 310 g/mol

m(Ca3(PO4)2 = n(Ca3(PO4)2) * M(Ca3(PO4)2) = 0.72 * 310 = 223.2 g

ответ 223.2 г