The reactions of chlorine

Explain why fluorine has a lower boiling point than chlorine.

Because Fluorine is smaller than chlorine, leading to the force between fluorine molecules being weaker.

Chlorine can be reacted with sodium hydroxide to form bleach. 

Write an ionic equation for the reaction between chlorine and cold dilute sodium hydroxide solution.

The ionic equation for the reaction between chlorine and cold dilute sodium hydroxide solution

`Cl_2 + 2OH^-) -> OCl^-) + Cl^-) + H_2O`

For the reaction of chlorine with water:

A. Write a balanced chemical equation

B. Give the oxidation numbers of chlorine before and after the reaction

C. Give one use for the process

D. What name is given to the type of this reaction?

A. The balanced chemical equation

`Cl _2 + H_2O → HCl + HOCl`

B. The oxidation number of chlorine before the reaction of 0 in Cl₂ and after the reaction of -1 in HCl and +1 in HOCl

C. Chlorination of water in water purification

D. The chlorine undergoes disproportionation in water

For the reaction of chlorine with cold dilute aqueous sodium hydroxide:

A. Write a balanced chemical equation

B. Give the oxidation numbers of chlorine before and after the reaction

C. Give one use for the process

D. What name is given to the type of this reaction?

A. The balanced chemical equation

`Cl _2 + 2NaOH → H _2O + NaCl + NaOCl`

B. The oxidation number of chlorine before the reaction of 0 in Cl₂ and after the reaction of -1 in NaCl and +1 in NaOCl

C. Killing bacteria when toilets are cleaned with bleach

D. Chlorine reacts with cold hydroxide ions in a disproportionation (‘self reduction-oxidation’) reaction

Explain why the reaction of chlorine with cold and with hot aqueous sodium hydroxide is an example of a disproportionation reaction.

Because the oxidation number of chlorine changes from 0 to +1 in NaClO and to 1 in NaCl. That means that chlorine has been simultaneously oxidised and reduced. Therefore, this is so-called disproportionation reaction.

When chlorine reacts with hot dilute sodium hydroxide a different product is formed. State the formula of the different product and the oxidation state of the chlorine atom in this compound.

The reaction that occurs with hot dilute sodium hydroxide

`3Cl_2 (aq) + 6NaOH (aq) -> 5NaCl (aq) + NaClO_3 (aq) + 3H_2O (l)`

The oxidation state of the chlorine atom in NaClO₃ is +5

Chlorine is widely used in water treatment plants. Chlorine is reacted with water to produce hydrochloric acid and another chlorine-containing acid.

Which row correctly describes the properties of the reaction?

The answer is A

The reaction of water with chlorine

`Cl _2 + H_2O → HCl + HOCl`

Chlorine is used to treat drinking water.

Which statement is correct?

A. Water reacts with chlorine to form hydrochloric acid and chloric(I) acid, HClO

B. When universal indicator is added to chloric(I) acid, HClO it turns blue then white

C. Chloric acid does not dissociate further when added to water

D. Chlorine reacts with cold sodium hydroxide to form sodium chloride and water only

The answer is A

B is incorrect because when universal indicator is added to chloric(I) acid, HClO it turns red then white

C is incorrect because `HClO (aq) -> H^+ (aq) + ClO^-) (aq)`

D is incorrecet because `Cl_2 + NaOH -> NaCl + NaClO + H_2O`

Which is the correct equation for the reaction of hot, dilute aqueous sodium hydroxide, NaOH, and chlorine, Cl₂?

A. `Cl_2 + 2NaOH → NaCl + NaClO + H_2O`

B. `1/2 Cl_2 + 2OH^-) → ClO^-) + H_2O + e^-`

C. `½ Cl_2 + 6OH^-) → ClO""_3^(-) + 3H_2O + e^-`

D. `3Cl_2 + 6NaOH → 3NaCl + 3NaClO_3 + H_2O`

The answer is C

A is incorrect because this is the equation for cold, dilute aqueous hydroxide and chlorine

B is incorrect because this is the half equation for cold, dilute aqueous hydroxide and chlorine

D is incorrect because it’s wrong in balanced equation

What is the main disinfectant formed when chlorine gas is added to water during purification?

A. HClO

B. HCl

C. ClO₂

D. CHCl₃

The answer is A

`Cl _2 (g) + H_2O (l) → HCl (aq) + HOCl (aq)`

B is incorrect because there is HCl generation in this reaction but it’s does not disinfect water

C and D are incorrect because they are not created in the reaction of chlorine gas with water