Halogen Oxyacids

Halogen Oxyacids

Oxygen-containing acids in which a halogen such as chlorine, bromine, or iodine serves as the central element.

Hypohalous, Halous, Halic, and Perhalic Acids

Name the four major halogen oxyacid families in order of increasing number of oxygen atoms.

HXO

General formula of a hypohalous acid.

HXO₂

General formula of a halous acid.

HXO₃

General formula of a halic acid.

HXO₄

General formula of a perhalic acid.

Hypohalous Acid

The halogen oxyacid family having the general formula HXO.

Halous Acid

The halogen oxyacid family having the general formula HXO₂.

Halic Acid

The halogen oxyacid family having the general formula HXO₃.

Perhalic Acid

The halogen oxyacid family having the general formula HXO₄.

Hypohalite Ion (XO⁻)

The conjugate-base oxyanion produced when a hypohalous acid loses H⁺.

XO⁻

General formula and charge of a hypohalite ion.

Halite Ion (XO₂⁻)

The conjugate-base oxyanion corresponding to a halous acid.

XO₂⁻

General formula and charge of a halite ion.

Halate Ion (XO₃⁻)

The conjugate-base oxyanion corresponding to a halic acid.

XO₃⁻

General formula and charge of a halate ion.

Perhalate Ion (XO₄⁻)

The conjugate-base oxyanion corresponding to a perhalic acid.

XO₄⁻

General formula and charge of a perhalate ion.

Hypo-___-ous → Hypo-___-ite

What naming relationship connects a hypohalous acid with its conjugate-base oxyanion?

___-ous → ___-ite

What naming relationship connects a halous acid with its corresponding oxyanion?

___-ic → ___-ate

What naming relationship connects a halic acid with its corresponding oxyanion?

Per-___-ic → Per-___-ate

What naming relationship connects a perhalic acid with its corresponding oxyanion?

Fewer Oxygen Atoms

The prefix hypo- identifies the member of a related oxyacid series containing relatively __________.

More Oxygen Atoms

The prefix per- identifies the member of a related oxyacid series containing relatively __________.

Hypochlorous Acid (HClO)

Name of the chlorine oxyacid HClO.

HClO

Chemical formula of hypochlorous acid.

Chlorous Acid (HClO₂)

Name of the chlorine oxyacid HClO₂.

HClO₂

Chemical formula of chlorous acid.

Chloric Acid (HClO₃)

Name of the chlorine oxyacid HClO₃.

HClO₃

Chemical formula of chloric acid.

Perchloric Acid (HClO₄)

Name of the chlorine oxyacid HClO₄.

HClO₄

Chemical formula of perchloric acid.

HClO, HClO₂, HClO₃, HClO₄

Give the formulas of hypochlorous, chlorous, chloric, and perchloric acid, respectively.

Hypochlorous → Chlorous → Chloric → Perchloric

Arrange the four principal chlorine oxyacids in order of increasing number of oxygen atoms.

Hypochlorite Ion (ClO⁻)

The conjugate base of hypochlorous acid.

ClO⁻

Chemical formula and charge of the hypochlorite ion.

Chlorite Ion (ClO₂⁻)

The conjugate base of chlorous acid.

ClO₂⁻

Chemical formula and charge of the chlorite ion.

Chlorate Ion (ClO₃⁻)

The conjugate base of chloric acid.

ClO₃⁻

Chemical formula and charge of the chlorate ion.

Perchlorate Ion (ClO₄⁻)

The conjugate base of perchloric acid.

ClO₄⁻

Chemical formula and charge of the perchlorate ion.

ClO⁻, ClO₂⁻, ClO₃⁻, ClO₄⁻

Give the formulas of hypochlorite, chlorite, chlorate, and perchlorate, respectively.

Hypochlorite → Chlorite → Chlorate → Perchlorate

Arrange the four principal chlorine oxyanions in order of increasing number of oxygen atoms.

Hypochlorous Acid → Hypochlorite

Complete the acid-to-anion relationship: HClO → ______.

Chlorous Acid → Chlorite

Complete the acid-to-anion relationship: HClO₂ → ______.

Chloric Acid → Chlorate

Complete the acid-to-anion relationship: HClO₃ → ______.

Perchloric Acid → Perchlorate

Complete the acid-to-anion relationship: HClO₄ → ______.

+1

Oxidation state of chlorine in HClO and ClO⁻.

+3

Oxidation state of chlorine in HClO₂ and ClO₂⁻.

+5

Oxidation state of chlorine in HClO₃ and ClO₃⁻.

+7

Oxidation state of chlorine in HClO₄ and ClO₄⁻.

+1, +3, +5, +7

Give the chlorine oxidation states in HClO, HClO₂, HClO₃, and HClO₄, respectively.

Increasing Oxidation State

Moving from hypochlorous acid to perchloric acid causes the oxidation state of chlorine to generally __________.

Hypofluorous Acid (HOF)

The unusual fluorine-containing hypohalous compound discussed in the lesson.

HOF

Chemical formula of hypofluorous acid.

Hydrogen Hypofluorite

A possibly more appropriate name suggested in the lesson for HOF because of its unusual chemistry.

Above −40 °C

HOF is very unstable and decomposes at temperatures above approximately __________.

Very Unstable

How would you describe the stability of HOF?

It Does Not Ionize in Water

What unusual aqueous behavior of HOF makes its classification as an acid questionable?

No Known Salts

How many salts of HOF are known according to the lesson?

Because HOF does not ionize in water and no salts are known.

Why does the textbook question whether "hypofluorous acid" is an appropriate name for HOF?

Chlorine and Bromine

Which two halogens react with water in a manner described as analogous to fluorine reacting with ice?

They Do Not Go to Completion

Do the reactions of chlorine and bromine with water proceed completely to products?

Halogen + Hypohalous Acid + Hydrohalic Acid

What general mixture results when chlorine or bromine reacts with water?

Cl₂ + H₂O ⇌ HClO + HCl

Chemical equation representing the reaction of chlorine with water.

Hypochlorous Acid and Hydrochloric Acid

Name the two acids formed when chlorine reacts reversibly with water.

Br₂ + H₂O ⇌ HBrO + HBr

Chemical equation representing the analogous reaction of bromine with water.

Hypobromous Acid and Hydrobromic Acid

Name the two acids formed when bromine reacts reversibly with water.

Only in Solution

Other than HOF, the hypohalous acids generally exist only __________.

Very Weak Acids

The hypohalous acids are generally classified as __________.

HOCl > HOBr > HOI

Order hypochlorous, hypobromous, and hypoiodous acid from strongest to weakest acid.

Hypochlorous Acid (HOCl)

Which is the strongest acid among HOCl, HOBr, and HOI?

Hypoiodous Acid (HOI)

Which is the weakest acid among HOCl, HOBr, and HOI?

Decreases Down the Group

How does the acid strength of HOCl, HOBr, and HOI change as the halogen moves down the group?

Hypochlorous Acid (HOCl)

Name of the hypohalous acid containing chlorine.

Hypobromous Acid (HOBr)

Name of the hypohalous acid containing bromine.

Hypoiodous Acid (HOI)

Name of the hypohalous acid containing iodine.

HOCl, HOBr, HOI

Give the formulas of hypochlorous, hypobromous, and hypoiodous acids.

Addition of Base

How can solutions containing hypohalite ions be produced from hypohalous acids?

Hypohalite Salts

Adding base to a hypohalous-acid solution produces salts containing __________.

Basic

Hypohalite ions, OX⁻, exhibit what acid-base character in aqueous solution?

They Can Be Isolated as Solids

Unlike most hypohalous acids themselves, what useful property applies to their salts?

Disproportionation

A redox process in which the same species is simultaneously oxidized and reduced.

Unstable Toward Disproportionation

Hypohalite ions generally exhibit what type of chemical instability in solution?

Hypochlorite

Which common hypohalite undergoes disproportionation relatively slowly?

Hypobromite and Hypoiodite

Which two hypohalite ions disproportionate rapidly even in the cold?

Slow

Compared with hypobromite and hypoiodite, disproportionation of hypochlorite is relatively __________.

Rapid

Hypobromite and hypoiodite undergo disproportionation at a relatively __________ rate, even when cold.

3XO⁻ → 2X⁻ + XO₃⁻

General equation for disproportionation of a hypohalite ion.

Halide and Halate

A hypohalite undergoing disproportionation generally forms these two types of products.

Oxidized and Reduced

In a disproportionation reaction, atoms of the same element are simultaneously __________ and __________.

3ClO⁻ → 2Cl⁻ + ClO₃⁻

Representative equation for disproportionation of hypochlorite.

Chloride and Chlorate

What chlorine-containing products form when hypochlorite disproportionates?

Sodium Hypochlorite (NaClO)

The active chlorine-containing compound commonly associated with household liquid bleach.

NaClO

Chemical formula of sodium hypochlorite.

Household Bleach

A common commercial application of sodium hypochlorite.

Hypochlorite Ion

The chemically active oxyanion in sodium hypochlorite.

Bleaching and Disinfection

Two major practical applications of hypochlorite chemistry.

Oxidizing Ability

The usefulness of hypochlorites in bleaching and disinfection largely results from their strong __________.