Group 17

Write an equation to represent the reaction of NaCl(s) with concentrated sulfuric acid.

Name this type of reaction.

Identify the chemical responsible for the steamy fumes.

The reaction of NaI(s) with concentrated sulfuric acid continues, forming several other products, including a dark grey solid.

Identify the chemical responsible for the dark grey solid and one other product of this further reaction.

• dark grey solid:
• other product:

Explain the differences in observations, at room temperature, when NaI(s) reacts with concentrated sulfuric acid compared to those for NaCl(s).

Complete the equation for the reaction of Br⁻ with excess concentrated H₂SO₄ at room temperature.

......Br⁻ + ......H⁺ + ......H₂SO₄ → ...............................................................................

Give the colours and states of chlorine, bromine and iodine at room temperature and pressure.

The halogens become less volatile down the group.

Explain this trend in volatility.

The halogens are oxidising agents.

State and explain the trend in oxidising power of the halogens.

State any observations that would be made on addition of concentrated sulfuric acid to

• solid sodium chloride,
• solid sodium iodide.

Give reasons for the difference in the observations in (i).

The addition of concentrated sulfuric acid to solid sodium bromide, $\text{NaBr}$, produces brown fumes and an acidic gas that decolourises acidified potassium manganate(VII) solution. This acidic gas is a significant contributor to acid rain.

Write the equation for the reaction of concentrated sulfuric acid with sodium bromide.

Excess aqueous silver nitrate is added to $\text{Z}$ in a test-tube. A yellow precipitate forms.

Explain the colour of this precipitate.

Aqueous ammonia is then added to the test-tube in (i). The mass of precipitate decreases.

Explain this observation.

What is the identity of $\text{Na}X$?

What gas, other than $\text{H}X$, would be formed if concentrated sulfuric acid were used with $\text{Na}X$ instead of phosphoric(V) acid?

Suggest why phosphoric(V) acid rather than concentrated sulfuric acid is used to make samples of $\text{H}X$ from the corresponding sodium salt.

Explain your answer.

What is the identity of $\text{Na}X$?

What gas, other than $\text{H}X$, would be formed if concentrated sulfuric acid were used with $\text{Na}X$ instead of phosphoric(V) acid?

Suggest why phosphoric(V) acid rather than concentrated sulfuric acid is used to make samples of $\text{H}X$ from the corresponding sodium salt.

Explain your answer.

State the trend in the volatility of the Group 17 elements down the group.

Explain this trend.

Iodine, $\text{I}_2$, can be displaced from $\text{NaI}(\text{aq})$, by chlorine, $\text{Cl}_2$.

Write an equation for this reaction.

Complete the table to give the colour and name of the precipitate formed in each reaction and the effect of the addition of an excess of aqueous ammonia to each of the precipitates formed.

Write an ionic equation, including state symbols, to show the reaction occurring when $\text{AgNO}_3(\text{aq})$ is added to $\text{NaI}(\text{aq})$.

Solid $\text{NaI}$ reacts with concentrated sulfuric acid to form purple fumes of $\text{I}_2(\text{g})$ and hydrogen sulfide gas, $\text{H}_2\text{S}(\text{g})$.

However, when solid $\text{NaCl}$ reacts with concentrated sulfuric acid the only gas produced is $\text{HCl}(\text{g})$.

Explain the difference in the reactions of concentrated sulfuric acid with $\text{NaI}$ and with $\text{NaCl}$. Your answer should refer to the role of the sulfuric acid in each reaction.

Suggest an equation for this reaction of chlorine with water.

Write an equation for the reaction of chlorine with hot aqueous sodium hydroxide.

Use oxidation numbers to explain why this is a redox reaction.

The elements of Group 17 are called halogens.

Complete Table 1.1.

Table 1.1

State the trend in volatility of the halogens chlorine, bromine and iodine. Explain your answer.

Construct an ionic equation for the reaction of bromine with sodium iodide.

Write an equation to describe the acid–base reaction that occurs when concentrated sulfuric acid reacts with NaBr.

Deduce which sodium halide, NaCl, NaBr or NaI, produces the largest percentage yield of hydrogen halide when concentrated sulfuric acid is added. Explain your answer by considering the relative reactivity of the halide ions as reducing agents.

identity of sodium halide:

explanation:

What will be seen when concentrated sulfuric acid is carefully added to solid sodium chloride?

Write a balanced equation for this reaction.

State one observation you would make when carrying out this reaction with solid sodium iodide.

Explain why hydrogen iodide is not a product of this reaction.

Aqueous silver nitrate is slowly added to aqueous sodium chloride and the resulting mixture is then shaken with an excess of aqueous ammonia.

Describe what you would observe at each stage of this process.

Write balanced equations, with state symbols, for all reactions that occur in this process.

The same process of adding aqueous silver nitrate followed by an excess of aqueous ammonia is repeated using aqueous sodium iodide instead of aqueous sodium chloride.

State two differences that would be observed with aqueous sodium iodide.

State what you would observe during this reaction.

The halogens chlorine, bromine and iodine are all volatile elements.

State and explain the trend in volatility down Group 17.

Write an equation for the reaction of chlorine with cold aqueous sodium hydroxide, $\text{NaOH}$.

Explain why it is a disproportionation reaction.

equation

explanation

One of the products of the reaction of chlorine with hot aqueous sodium hydroxide differs from those in (c)(i).

Identify the compound that is formed in this reaction that is different from that formed in the reaction in (c)(i).

State and explain the use of chlorine in water purification.

State what you would observe during this reaction.

The halogens chlorine, bromine and iodine are all volatile elements.

State and explain the trend in volatility down Group 17.

Write an equation for the reaction of chlorine with cold aqueous sodium hydroxide, $\text{NaOH}$.

Explain why it is a disproportionation reaction.

equation

explanation

One of the products of the reaction of chlorine with hot aqueous sodium hydroxide differs from those in (c)(i).

Identify the compound that is formed in this reaction that is different from that formed in the reaction in (c)(i).

State and explain the use of chlorine in water purification.

Complete the table below, stating the colour of each element in its normal state at room temperature.

By considering your answers to (a) and (b), predict the physical state of BrCl at room temperature. Explain your answer.

physical state:

explanation:

Suggest the colour of BrCl.

Describe what would be seen when $\text{Cl}_2$ is bubbled through aqueous KI for several minutes.

initially:

after several minutes:

Construct an equation for the reaction that occurs.

Suggest an equation for the reaction that occurs between BrCl and aqueous KI.

How do $\text{Cl}_2$ and BrCl behave in these reactions?