45) Balanced chemical reaction:
3Ca(OH)₂(aq) + 2H₃PO₄(aq) → Ca₃(PO₄)₂(aq) + 6H₂O(l).
Balanced ionic equation:
3Ca²⁺(aq) + 6OH⁻(aq) + 6H⁺(aq) + 2PO₄³⁻(aq) → 3Ca²⁺(aq) + 2PO₄³⁻(aq)+ 6H₂O(l).
Balanced net ionic equation: 6OH⁻(aq) + 6H⁺(aq) → 6H₂O(l).
This reaction is example of neutralization reaction.
46) Answer is: 67.2 liters of oxygen are needed to react completely.
Balanced chemic equation: 2H₂S(g) + 3O₂(g) → 2H₂O(l) + 2SO₂(g).
V(H₂S) = 45.0 L; volume of hydrogen sulfide.
Vm = 22.4 L/mol; molar volume at STP.
n(H₂S) = 45 L ÷ 22.4 L/mol.
n(H₂S) = 2.01 mol; amount of hydrogen sulfide.
From balanced chemical reaction: n(H₂S) : n(O₂) = 2 : 3.
n(O₂) = 3 mol; amount of oxygen.
V(O₂) = 3 mol · 22.4 L/mol.
V(O₂) = 67.2 L; volume of oxygen.
47) The azimuthal quantum number (l) determines its orbital angular momentum and describes the shape of the orbital.
s-orbitals (for example 1s, 2s) are spherically symmetric around the nucleus of the atom.
p-orbitals are dumb-bell shaped. l = 0,1...n-1, when l = 1, that is p subshell.
d-orbitals are butterfly shaped.
f-orbitals are similar to the d orbital, but cut in half (eight lobes instead of four).
48) Answer is: Ionic bond is the electrostatic attraction between oppositely charged ions (cations and anions).
For example, compound magnesium chloride (MgCl₂) has ionic bond.
Magnesium (Mg) transfers two electrons, and form positive cation Mg²⁺, to two chlorine atoms (Cl), which form negative anions Cl⁻.
Magnesium is metal from group 2 and chlorine is nonmetal from group 17 of the Periodic table.
