Exam code: 9701
Chlorine is widely used in water treatment plants. When chlorine reacts with water, hydrochloric acid and another chlorine-containing acid are produced.
Which row describes this reaction?
moles of Cl2 reacting | moles of HCl produced | identity of the other acid | |
|---|---|---|---|
A | 1 | 1 | HClO |
B | 2 | 3 | HClO2 |
C | 3 | 5 | HClO3 |
D | 4 | 7 | HClO4 |
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When chlorine reacts with cold, dilute aqueous sodium hydroxide, the following reaction occurs.
Cl2 (aq) + 2NaOH (aq) → NaCl (aq) + NaClO (aq) + H2O (l)
Which statement is correct?
The chlorine has only been oxidised
The oxidation number of Cl in NaClO is 0
The chlorine is simultaneously oxidised and reduced
The oxidation number of Cl in Cl2 is -1
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When chlorine reacts with hot, concentrated aqueous sodium hydroxide, the following reaction occurs.
3Cl2 (g) + 6NaOH (aq) → 5NaCl (aq) + NaClO3 (aq) + 3H2O (l)
Which row shows the oxidation state of chlorine in each substance?
Cl2 | NaCl | NaClO3 | |
|---|---|---|---|
A | 0 | −1 | +5 |
B | 0 | +1 | −5 |
C | 0 | +1 | −3 |
D | 0 | −1 | +3 |
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Chlorine is used to treat drinking water.
Which statement is correct?
Water reacts with chlorine to form hydrochloric acid and chloric(I) acid, HClO
When universal indicator is added to chloric(I) acid, HClO, it turns blue then white
Chloric(I) acid does not dissociate when added to water
Chlorine reacts with cold, dilute aqueous sodium hydroxide to form sodium chloride and water only
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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) + 3NaClO (aq) + 3H2O (l)
Which statement about this reaction is not correct?
A bleaching solution remains after the reaction.
Effervescence is observed.
The nitrogen is oxidised.
The final solution gives a precipitate with acidified aqueous silver nitrate.
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Which equation represents the oxidation of chlorine in its reaction with hot, concentrated aqueous sodium hydroxide?
Cl2 + 2NaOH → NaCl + NaClO + H2O
Cl2 + 2OH- → ClO- + H2O + e-
Cl2 + 6OH- → ClO3- + 3H2O + 5e-
3Cl2 + 6NaOH → 5NaCl + NaClO3 + 3H2O
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When chlorine gas is added to water during purification, which compound is the main disinfectant formed?
HClO
HCl
ClO2
CHCl3
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When chlorine is bubbled through aqueous sodium hydroxide, different substances are formed depending on the conditions.
Which statement is not correct?
In hot, concentrated NaOH (aq), ClO3– (aq) ions are formed.
In cold, dilute NaOH (aq), ClO– (aq) ions are formed.
The oxidation state of chlorine changes from 0 to +3
Disproportionation of chlorine occurs in both cold, dilute and hot, concentrated aqueous solutions.
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Which statement describes the reaction of chlorine with water?
Chlorine undergoes only oxidation in the reaction, forming HClO (aq)
Chlorine undergoes only reduction in the reaction, forming HCl (aq)
Chlorine undergoes both oxidation and reduction in the reaction, forming HCl (aq) and HClO (aq)
Chlorine undergoes both oxidation and reduction in the reaction, forming HCl (aq) and HClO3 (aq)
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Aqueous sodium chlorate(I) is added to aqueous potassium bromide. A brown solution is produced along with aqueous sodium chloride.
Which statement is correct?
The oxidation state of chlorine in NaClO is +5
Chlorine gas is produced
Bromide ions are oxidised in this reaction
NaClO is the reducing agent
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