Video Transcript
Which of the following ionic
compounds of chloride is insoluble in water? (A) Potassium chloride, (B) silver
chloride, (C) aluminum chloride, (D) magnesium chloride, or (E) sodium chloride.
The question is asking us to
identify the compound that is insoluble in water, which means when mixed with water,
the compound will be unable to be dissolved. This means the ionic compound,
which is composed of cations and anions, when added to water, would not break apart
into its respective ions and would not dissolve in the water, likely settling at the
bottom of the container. We can identify the insoluble
compound by referencing the water solubility rules.
Let’s first look at compounds that
are considered soluble in water and what ions they contain. Compounds containing alkaline metal
cations or lithium, sodium, potassium, rubidium, or cesium ions are soluble in water
as well as compounds containing ammonium ions, nitrate ions, bicarbonate ions,
chlorate ions, or acetate ions. Compounds containing halide ions
such as chloride ions, bromide ions, or iodide ions are also soluble in water unless
the compound also contains silver ions, mercury(I) ions, or lead(II) ions. Compounds containing sulfate ions
are soluble unless the compound also contains silver, calcium, strontium, barium,
mercury(I), or lead(II) ions.
Let’s have a look at the ions that
cause compounds to be insoluble in water. Compounds containing carbonate
ions, phosphate ions, sulfide ions, or hydroxide ions are generally considered
insoluble in water unless ions of lithium, sodium, potassium, rubidium, cesium, or
ammonium are also present. Compounds containing sulfide ions
have additional exceptions to their insolubility when ions of calcium, barium, or
strontium are present with compounds containing hydroxide ions having the same
additional exceptions.
The ionic compounds we are working
with are all chlorides, which we can see from the names of the compounds given in
the answer choices. If we locate our solubility rule
regarding compounds containing chloride ions, we can see that chloride compounds are
generally water-soluble, unless the compound also contains silver, mercury(I), or
lead(II) cations.
Let’s have a look at the answer
choices. Answer choice (A) contains
potassium ions, which is an alkali metal, and this compound is therefore soluble in
water with no exceptions. We can eliminate answer choice
(A). Answer choice (B) contains
silver. When a chloride compound contains
silver, the compound is insoluble as listed in the exception to the solubility of
chloride-containing compounds. Therefore, answer choice (B) is the
compound that is insoluble in water. We can confirm this as answer
choices (C), (D), and (E) all contain cations that are not listed as exceptions to
the solubility of chloride-containing compounds. Answer choices (C), (D), and (E)
are all soluble in water.
Therefore, the ionic compound of
chloride that is insoluble in water is answer choice (B), silver chloride.
