In a complex ion, each molecule or ion that donates a lone pair of electrons to bond with the central metal is called a ligand.
Missing Word
ligand
A ligand is a molecule or ion, such as H2O, NH3 or CN-, that bonds to a central metal atom or ion by donating an electron pair. Ligands act as Lewis bases toward the metal.
Category: Complex Ions
Question 2
When BF3 bonds to NH3 through a coordinate covalent bond, the single combined species that results is called an adduct.
Missing Word
adduct
An adduct is the compound or ion formed when a Lewis acid and a Lewis base join through a coordinate covalent bond. Here the nitrogen of NH3 donates its lone pair to the electron-deficient boron of BF3.
Category: Lewis Acids and Bases
Question 3
A solution in which the ion product of a slightly soluble salt is smaller than its Ksp is described as unsaturated, so more of the solid can dissolve.
Missing Word
unsaturated
An unsaturated solution has fewer dissolved ions than equilibrium allows, so Q is less than Ksp and any added solid dissolves until Q rises to Ksp.
Category: Predicting Precipitation
Question 4
Black-and-white photographic processing removes unexposed silver bromide by dissolving it in a solution of sodium thiosulfate, which binds Ag+ in a soluble complex.
Missing Word
thiosulfate
Thiosulfate ion, S2O3 2-, forms the stable complex Ag(S2O3)2 3- with silver ion. Removing free Ag+ couples complex formation to dissolution, so the otherwise insoluble silver bromide dissolves.
Category: Coupled Equilibria
Question 5
When a water molecule donates one of its lone pairs to a hydrogen ion, the cation formed is the hydronium ion.
Missing Word
hydronium
The hydronium ion, H3O+, forms when the oxygen of water donates a lone pair to H+ through a coordinate covalent bond. Water acts as the Lewis base and H+ as the Lewis acid.
Category: Lewis Acids and Bases
Question 6
In a solubility product expression, each ion concentration is raised to a power equal to that ion's coefficient in the balanced dissolution equation.
Missing Word
coefficient
The stoichiometric coefficient of each ion in the dissolution equation becomes its exponent in Ksp. For PbI2, iodide has a coefficient of 2, so its concentration is squared.
Category: Solubility Product
Question 7
Toothpastes that contain the anion fluoride make enamel more resistant to acid because this ion replaces hydroxide in the enamel mineral and reacts less with H+.
Missing Word
fluoride
Fluoride ion replaces hydroxide in calcium hydroxyapatite to form fluorapatite. Because fluoride is a much weaker base than hydroxide, the new mineral reacts less with acids from mouth bacteria and resists decay.
Category: Coupled Equilibria
Question 8
Metal carbonates and sulfides dissolve better in acidic solution because each of these anions acts as a base that combines with H+.
Missing Word
base
A base accepts H+. When carbonate or sulfide ions combine with H+, they are removed from solution, so the dissolution equilibrium of the salt shifts toward dissolved ions. Anions of strong acids, such as chloride, are too weak as bases to show this effect.
Category: Coupled Equilibria
Question 9
Each silver ion in the complex formed when silver chloride dissolves in aqueous ammonia is bonded to 2 ammonia molecules.
Missing Word
2
Silver ion forms the complex ion Ag(NH3)2+, in which two ammonia molecules each donate a lone pair to Ag+. Its large formation constant pulls Ag+ out of solution and dissolves the silver chloride.
Category: Complex Ions
Question 10
In the electron-pair model of acids and bases, an acid is any species that can act as an electron-pair acceptor.
Missing Word
acceptor
In the Lewis model, an acid is an electron-pair acceptor and a base is an electron-pair donor. This definition includes species with no hydrogen at all, such as BF3 and metal cations.
Category: Lewis Acids and Bases
Question 11
A solution that temporarily holds an ion product above Ksp without any solid forming is described as supersaturated.
Missing Word
supersaturated
A supersaturated solution contains more dissolved solute than equilibrium allows. It is unstable, and once crystals begin to form, solid precipitates until the ion product falls to Ksp.
Category: Predicting Precipitation
Question 12
When the ion product of a salt exceeds its Ksp, the excess ions come out of solution as a solid called a precipitate.
Missing Word
precipitate
A precipitate is an insoluble solid that forms from dissolved ions. It continues to form until the ion product falls back to the value of Ksp.
Category: Predicting Precipitation
Question 13
Patients can safely drink a suspension of the sulfate of barium before X-ray imaging of the digestive tract because so little of the compound dissolves.
Missing Word
barium
Barium sulfate has a very small Ksp, so the concentration of the toxic Ba2+ ion it releases stays tiny, while the dense solid blocks X-rays and outlines the digestive tract.
Category: Molar Solubility
Question 14
For a salt of formula MX2 dissolving in pure water, Ksp equals 4 times the cube of its molar solubility.
Missing Word
cube
If the molar solubility is s, then [M2+] = s and [X-] = 2s, so Ksp = s(2s)^2 = 4s^3. Finding s therefore requires taking a cube root.
Category: Molar Solubility
Question 15
For a given salt, the numerical value of Ksp changes only when the temperature changes.
Missing Word
temperature
Like every equilibrium constant, Ksp depends on temperature. Adding common ions, acids or ligands changes how much of the salt dissolves, but not the value of Ksp itself.
Category: Solubility Product