[2 Mark Question Answer]

Question 12 Marks

Sulphuric acid is manufactured by the contact process
Name the chemical used to dissolve $SO_3$ and also name the product formed. Give all the main reactions to this process.

Answer

The chemical used to dissolve $SO_3$ is concentrated sulphuric acid. The product formed is the oleum.
$SO_3 + H_2SO_4 \rightarrow H_2S_2O_7$

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Question 22 Marks

Sulphuric acid is manufactured by the contact process
Why $H_2SO_4$ is not obtained by directly reacting $SO_3$ with water.

Answer

Sulphuric acid is not obtained directly by reacting $SO_3$ with water because the reaction is highly exothermic which produce the fine misty droplets of sulphuric acid that is not directly absorbed by water.

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Question 32 Marks

Sulphuric acid is manufactured by the contact process.
Give two balanced equations to obtain $SO_2$ in this process.

Answer

Two balanced equations to obtain $SO_2$ is:
(i) $4FeS_2 + 110_2 \rightarrow 2Fe_2O_3 + 8SO_2$
(ii) $S + O_2 \rightarrow SO_2$

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Question 42 Marks

Give reason for the following:
Brisk effervescence is seen when oil of vitriol is added to sodium carbonate.

Answer

When sulphuric acid is added to sodium carbonate it liberates carbon dioxide which produces brisk effervescence.
$Na_2CO_3 + H_2SO_4 \rightarrow Na_2SO_4 + H_2O + CO_2 ↑$

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Question 52 Marks

Give a reason for the following:
Sulphuric acid forms two types of salts with $NaOH$

Answer

Two types of salts are formed when sulphuric acid reacts with $NaOH$ because sulphuric acid is dibasic.
$NaOH + H_2SO_4 \rightarrow NaHSO_4 + H_2O$
$2NaOH + H_2SO_4 \rightarrow Na_2SO_4 + 2H_2O$

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Question 62 Marks

What property of conc. $H_2SO_4$ is made use of the following case? Give an equation for the reaction on the same:
Its reaction with (i) ethanol (ii) carbon

Answer

(i) Ethanol
$C +2 H _2 SO _4 \longrightarrow CO _2+2 H _2 O +2 SO _2 \uparrow$
(ii) Carbon
$C _2 H _5 OH \xrightarrow[170^{\circ} C ]{\text { conc } \cdot H _2 SO _4} \underset{\text { Ethylene }}{ C _2 H _4 \uparrow}+ H _2 O$

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Question 72 Marks

What property of conc. $H _2 SO _4$ is made use of the following case? Give an equation for the reaction on the same: Hydrogen sulphide gas is passed through concentrated sulphuric acid.

Answer

Due to its oxidizing property Hydrogen sulphide gas is passed through concentrated sulphuric acid to liberate sulphur dioxide and sulphur is formed.
$H_2S + H_2SO_4 \rightarrow S + 2H_2O + SO_2$

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Question 82 Marks

What property of conc. $H_2SO_4$ is made use of the following case? Give an equation for the reaction on the same:
as a source of hydrogen by diluting it and adding a strip of magnesium.

Answer

Magnesium is present above hydrogen in the reactivity series so sulphuric acid is able to liberate hydrogen gas by reacting with magnesium strip.
$Mg + H_2SO_4 \rightarrow MgSO_4 + H_2$

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Question 92 Marks

What property of conc. $H_2SO_4$ is made use of the following case? Give an equation for the reaction on the same:
In the production of $HCI$ gas when it reacts with chloride.

Answer

Due to its reducing property. i.e, it is a non-volatile acid.
$\underset{\text { Conc }}{ NaCl }+ H _2 SO _4 \longrightarrow NaHSO _4+ HCl$

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Question 102 Marks

Why is $H_2SO_4$ is not used as a drying agent for $H_2S$?

Answer

Sulphuric acid is not used as a drying agent for $H_2S$ because it reacts with $H_2S$ to form sulphur.
$H_2SO_4 + H_2S \rightarrow 2H_2O + SO_2 + S ↓$

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Question 112 Marks

Write a balanced chemical equation : when hot and concentrated sulphuric acid reacts with the following : Copper

Answer

When sulphuric acid reacts with copper it forms copper sulphate and sulphur dioxide.
$Cu + H_2SO_4 \rightarrow CuSO_4 + 2H_2O + SO_2 $↑

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Question 122 Marks

Write a balanced chemical equation : when hot and concentrated sulphuric acid reacts with the following : Carbon

Answer

When sulphuric acid reacts with carbon it forms carbon dioxide and sulphur dioxide gas.
$C +2 H _2 SO _4 \longrightarrow CO _2+2 H _2 O +2 SO _2 \uparrow$

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Question 132 Marks

Write a balanced chemical equation : when hot and concentrated sulphuric acid reacts with the following :
Sugar

Answer

When sulphuric acid reacts with sugar it forms carbon
$C _{12} H _{22} O _{11} \xrightarrow{\text { conc } \cdot H _2 SO _4} 12 C +11 H _2 O$

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Question 142 Marks

Write a balanced chemical equation : when hot and concentrated sulphuric acid reacts with the following :
$NaOH$

Answer

When sulphuric acid reacts with sodium hydroxide it neutralizes base to form sodium sulphate.
$2NaOH + H_2SO_4 \rightarrow Na_2SO_4 + 2H_2O$

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Question 152 Marks

Write a balanced chemical equation : when hot and concentrated sulphuric acid reacts with the following :
Sulphur

Answer

When sulphuric acid reacts with sulphur the product formed is Sulphur dioxide is formed.
$S +2H_2SO_4\rightarrow 3SO_2 + 2H_2O$

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Question 162 Marks

Give a chemical test to distinguish between : dilute sulphuric acid and dilute hydrochloric acid,(using lead nitrate solution).

Answer

Sulphuric acid precipitates the insoluble sulphate from lead nitrate solution.
$Pb \left( NO _3\right)_2+ H _2 SO _4 \longrightarrow PbSO _4+2 HNO _3$
Lead nitrate reacts with hydrochloric acid to give a white ppt. of lead chloride.
$Pb \left( NO _3\right)_2+2 HCl \longrightarrow PbCl _2+2 HNO _3$

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Question 172 Marks

Give two balanced reactions of each type to show the following properties of sulphuric acid :
Dehydrating nature

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Question 182 Marks

Why is water not added to concentrated $H_2SO_4$ in order to dilute it?

Answer

Water is not added to concentrated acid since it is an exothermic reaction. If water is added to the acid, there is a sudden increase in temperature and the acid being in bulk tends to spurt out with serious consequences.

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Chemistry [2 Mark Question Answer]

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