Write the conditions to maximise the yield of H 2 SO 4 by contact process.

The key step to maximise the yield of H 2 SO 4 is the oxidation of SO 2 to SO 3 in presence of V 2 O 5 catalyst. 2 SO 2 g + O 2 g ⇌ V 2 O 5 2 SO 3 g ; ∆ H ° = - 196 . 6 kJ mol - 1 The above reaction is exothermic, reversible and the forward reaction leads to a decrease in volume. So, in accordance with Le Chatelier's principle, low temperature and high pressure are the favourable conditions for maximum yield. But the temperature should not be too low since the rate of reaction will become slow. The optimum conditions in the contact process to maximise the yield of sulphuric acid in an industrial plant is a pressure of 2 bar and temperature around 720 K .

Write the reactions of F 2 and Cl 2 with water.

When chlorine gas reacts with water, it gives hydrochloric acid and hypochlorous acid. Cl 2 g Chlorine + H 2 O l Water → HCl aq Hydrochloric acid + HOCl aq Hypochlorous acid Fluorine gas on reaction with water gives hydrogen ions, fluoride ions, oxygen gas as products. 2 F 2 g + 2 H 2 O l → 4 H + aq + 4 F - aq + O 2 g

ClF 3 exists but FCl 3 does not exist. Why?

ClF 3 exists because chlorine is a period 3 element and has vacant d -orbitals, due to which it can easily expand its octet. Fluorine on the other hand is a period 2 element and has no d -orbitals to expand its octet and form bond with three chlorine atoms to form FCl 3 .

Can PCl 5 act as an oxidising as well as a reducing agent? Justify.

Phosphorous pentachloride can only act as an oxidising agent. PCl 5 cannot act as a reducing agent because in PCl 5 , the oxidation state of phosphorus is + 5 , and it is not possible for phosphorus to increase its oxidation state beyond + 5 , whereas it can easily act as an oxidising agent because it can decrease its oxidation state from + 5 to a lower oxidation state.

E M B I B E

NEW SYSTEMATIC MODERN CHEMISTRY>Chapter 7 - p-Block Elements>REVIEW EXERCISES>Q 14

MEDIUM

12th West Bengal Board

IMPORTANT

Earn 100

What is meant by ozonolysis?

Important Questions on p-Block Elements

MEDIUM

12th West Bengal Board

IMPORTANT

NEW SYSTEMATIC MODERN CHEMISTRY>Chapter 7 - p-Block Elements>REVIEW EXERCISES>Q 14

What is meant by tailing of mercury?

HARD

12th West Bengal Board

IMPORTANT

NEW SYSTEMATIC MODERN CHEMISTRY>Chapter 7 - p-Block Elements>REVIEW EXERCISES>Q 15

Why is $O - O$ bond length in ozone ( $128 pm$ ) more than in $O_{2}$ ( $122 pm$ )?

MEDIUM

12th West Bengal Board

IMPORTANT

NEW SYSTEMATIC MODERN CHEMISTRY>Chapter 7 - p-Block Elements>REVIEW EXERCISES>Q 15

Why ozone is used in improving the atmosphere of crowded places such as cinema halls, tube railway, etc.

MEDIUM

12th West Bengal Board

IMPORTANT

NEW SYSTEMATIC MODERN CHEMISTRY>Chapter 7 - p-Block Elements>REVIEW EXERCISES>Q 16

Write balanced chemical equations for the preparation of ${SO}_{2}$ from a sulphite and sulphide ores.

MEDIUM

12th West Bengal Board

IMPORTANT

NEW SYSTEMATIC MODERN CHEMISTRY>Chapter 7 - p-Block Elements>REVIEW EXERCISES>Q 17

What happens when

H_{2} S

reacts with

{SO}_{2}

.

MEDIUM

12th West Bengal Board

IMPORTANT

NEW SYSTEMATIC MODERN CHEMISTRY>Chapter 7 - p-Block Elements>REVIEW EXERCISES>Q 17

What happens when ${SO}_{2}$ is passed through caustic soda solution?

MEDIUM

12th West Bengal Board

IMPORTANT

NEW SYSTEMATIC MODERN CHEMISTRY>Chapter 7 - p-Block Elements>REVIEW EXERCISES>Q 18

${SO}_{3}$ formed by the oxidation of ${SO}_{2}$ is not directly dissolved in water. Give reason.

HARD

12th West Bengal Board

IMPORTANT

NEW SYSTEMATIC MODERN CHEMISTRY>Chapter 7 - p-Block Elements>REVIEW EXERCISES>Q 18

Sulphuric acid having concentration greater than $98.5 % H_{2} {SO}_{4}$ cannot be obtained by distillation of an aqueous solution of $H_{2} {SO}_{4}$ .

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