2.3 Group 17

Iodine trichloride, ICl₃, is made by reacting iodine with chlorine.

I₂ (s) + Cl₂ (g)  2ICl (s) ;    ∆H^o = +14 kJ mol^–1

ICl (s) + Cl₂ (g)  ICl₃ (s) ;   ∆H^o = –88 kJ mol^–1

By using the data above, what is the enthalpy change of the formation for solid iodine trichloride?

An unlabeled powder is known to be either a single sodium halide or a mixture of two different sodium halides. 

To determine what the powder consists of a sample of the powder was first dissolved in water. Then acidified aqueous silver nitrate was added to the new solution, and a pale yellow precipitate was formed. When concentrated aqueous ammonia was added, the precipitate partly dissolved, leaving a darker yellow precipitate. 

What might the powder have consisted of?

The following two experiments are carried out with anhydrous potassium chloride and observations X and Y are made at the end of each experiment. 

The potassium chloride is dissolved in aqueous silver nitrate, and this is then added to aqueous ammonia- observation X. 

Concentrated sulfuric acid is added to the potassium chloride, and the fumes produced are bubbled into aqueous potassium iodide solution - observation Y. 

What are the observations X and Y?

Element 85, astatine, is a halogen. If concentrated sulfuric acid is added to sodium astatide the resultant products are a mix of astatine, hydrogen astatide, hydrogen sulfide and sodium sulfate.

Which product is formed by the oxidation of one of the constituents of sodium astatide?

Q is a salt of one of the Group 17 elements chlorine, bromine, iodine, or astatine.

The reaction scheme shows a series of reactions using a solution of Q as the starting reagent.

What could Q be?

Two students, R and S, were asked to draw bar charts to represent how some properties of the halogens and their compounds differ in magnitude. Their diagrams are shown.

Which of the student’s diagrams are correct?

Solid potassium halides react with concentrated sulfuric acid, according to the following equations.

Reaction 1:     2KCl + H₂SO₄ → K₂SO₄ + 2HCl

Reaction 2:     2KBr  +  2H₂SO₄  →  K₂SO₄  +  SO₂  +  Br₂  +  2H₂O

Reaction 3:     8KI +  5H₂SO₄  →  4K₂SO₄  +  H₂S  +  4I₂  + 4H₂O

What is the largest change in the oxidation number of sulfur in each of these reactions?

X, Y and Z represent different halogens. The table shows the results of nine experiments in which aqueous solutions of X₂, Y₂ and Z₂ were separately added to separate aqueous solutions containing X^-, Y^- and Z^- ions.

Which row in the following table contains the ions X-, Y- and Z-  in order of their decreasing strength as reducing agents?

Which row represents the correct electrodes used to manufacture chlorine from brine in a diaphragm cell?

The following report appeared in a newspaper:

Which of the following observations is incorrect in the report?

What is the complete list of all the products from the reaction of potassium bromide with concentrated sulfuric acid?

On contact with a hot glass rod, which gaseous hydride most readily decomposes into its elements?

What happens when chlorine is bubbled through an aqueous sodium hydroxide solution?

A molecule of chlorine has a relative molecular mass of 72.

Which properties of the atoms in this molecule are the same?

Astatine is the element below iodine in Group 17 of the Periodic Table.

Which statement is most likely to be true for astatine?

Which graph correctly illustrates a trend found in the halogen group?

When the yellow liquid NCl₃ is stirred into aqueous sodium hydroxide, the reaction that occurs can be represented by the following equation.

2NCl₃ (l) + 6NaOH (aq)  N₂ (g) + 3NaCl (aq) + 3NaOCl (aq) + 3H₂O (l)

What will be the result of this reaction?

Compound X readily conducts electricity when added to water to produce a solution but does not conduct electricity in its liquid state.

Which of the following could X be?