Determine the number of moles of each type of monatomic or polyatomic ion in one mole of the following compounds. for each polyatomic ion, determine the number of moles of each atom present in one mole of the ion.
a. kno3
b. na2so4
c. ca(oh)2
d. (nh4)2so3
e. ca3(po4)2
f. al2(cro4)3

KNO₃ → 1 mol of K⁺ ; 1 mol of nitrate (1 mol of oxygen + 3 mol of nitrogen)

Na₂SO₄ → 2 mol of Na⁺ ; 1 mol of sulfate ( 1 mol of sulfur + 4 mol of oxygen)

Ca(OH)₂ → 1 mol of calcium; 2 moles of hydroxide

(NH₄)₂SO₃ → 2 mol of ammonium; 2 mol of sulfite (1 mol of sulfur + 3 mol of oxygen)

Ca₃(PO₄)₂ → 3 mol of calcium: 2 mol of phosphate (1 mol of phosphorus + 4 mol of oxygen)

Al₂(CrO₄)₃ → 2 mol of aluminum ; 3 mol of cromate (1 mol of Cr + 4 mol of oxygen)

Explanation:

Let's verify all the dissociations:

KNO₃  → K⁺  + NO₃⁻

Na₂SO₄  → 2Na⁺  +  SO₄⁻²

Ca(OH)₂   → Ca²⁺  +  2OH⁻

(NH₄)₂SO₃ → 2NH₄⁺  +  2SO₃⁻²

Ca₃(PO₄)₂   → 3Ca²⁺  +  2PO₄⁻³

Al₂(CrO₄)₃ → 2Al³⁺  +  3CrO₄⁻²

we can conclude that the melting point of table salt is above room temperature (it's actually 801 deg c). the melting point of mercury must be below room temperature (- 39 deg c).