Tag: chemistry

Questions Related to chemistry

The wrong statements about $\displaystyle NH _{3}$ is :

chemistry nitrogen and sulfur ammonia and fertilizers preparation of ammonia-laboratory method and haber's process ammonia

  1. it is oxidised with oxygen at $\displaystyle 700^{\circ}C$ in the presence of platinum

  2. it gives black precipitate with calomel

  3. it can be dried by $\displaystyle P _{2}O _{5},\ H _{2}SO _{4}\, $and$\, CaCl _{2}$

  4. it gives white fumes with HCI

Show answer
Correct Option: C
Explanation:
$NH _3$ is oxidised to nitric oxide and water with oxygen at $700^oC $ in the presence of platinum.
Aqueous ammonia reacts with calomel $Hg _2Cl _2$ to produce metallic mercury, a black precipitate. 
$CaO$ calcium oxide is used for drying of ammonia. Because $CaO$ being basic in nature does not react with $NH _3$ while $P _2O _5, $ conc. $H _2SO _4 \ $and$ \ CaCl _2$ reacts with it.
$CaO + H _2O + NH _3 \rightarrow NH _3 + Ca(OH) _2$
$CaCl _2 + 8NH _3 \rightarrow CaCl _2.8NH _3$
$P _2O _5 + 3H _2O + 6NH _3 \rightarrow 2(NH _4) _3PO _4$
$H _2SO _4 + NH _3 \rightarrow (NH _4) _2SO _4$
$NH _3$ gives White fumes of $NH _4Cl$ with $HCl$.
Nitrogen reacts with a metal $M$ to produce a compound $X$. This compound $X$ when dissolved in water forms pungent gas $Y$ which can be identified easily by the formation of white fumes in the presence of $HCl$.

Identify Y:
chemistry nitrogen and sulfur ammonia and fertilizers preparation of ammonia-laboratory method and haber's process ammonia

  1. Nitrogen dioxide

  2. Ammonia

  3. Nitrous oxide

  4. Nitric oxide

Show answer
Correct Option: B
Explanation:
$ 3Ca+{ N } _{ 2 }\xrightarrow [ \Delta  ]{  } { Ca } _{ 3 }{ N } _{ 2 } $

$ { Ca } _{ 3 }{ N } _{ 2 }+6{ H } _{ 2 }O\xrightarrow [  ]{  } 3Ca{ (OH) } _{ 2 }+2N{ H } _{ 3 } $
From the reaction we can see that the metal $ M $ is $Ca$ and pungent gas $ Y $ is Ammonia. 

Cyanamide process is used in formation of-

chemistry nitrogen and sulfur ammonia and fertilizers preparation of ammonia-laboratory method and haber's process ammonia

  1. $N _2$

  2. $HNO _3$

  3. $NH _3$

  4. $PH _3$

Show answer
Correct Option: C
Explanation:

Cyanamide process is a nitrogen fixation process in which Calcium Carbide and nitrogen react with each other at a high temperature to form Calcium Cyanamide.
The following reaction takes place:

$CaC _2$ $+$ $N _2$ $ \longrightarrow $ $CaCN _2$ $+$ $C$
At high temperature Calcium Cyanamide react with steam as follows:
$CaCN _2$ $+$ $3H _2O$ $\longrightarrow $ $CaCO _3$ $+$ $2NH _3$
Hence, $NH _3$ is formed.

In the Haber process for the industrial manufacturing of ammonia involving the reaction
${ N } _{ 2 }(g)+3{ H } _{ 2 }(g)\rightleftharpoons 2{ NH } _{ 3 }(g)$ at $200atm$ pressure in the presence of a catalyst, a temperature of about ${ 500 }^{ o }C$ is used. This is considered as optimum temperature for the process because:

chemistry nitrogen and sulfur ammonia and fertilizers preparation of ammonia-laboratory method and haber's process ammonia

  1. yield is maximum at this temperature

  2. catalyst is active only at this temperature

  3. energy needed for the reaction is easily obtained at this temperature

  4. rate of the catalytic reaction is fast enough while the yield is also appreciable for this exothermic reaction at this temperature

Show answer
Correct Option: A
Explanation:

In order to yield the maximum yield of ammonia, the temperature is lowered though $500^oC$ is not a low temperature. This temperature $(500^oC)$ is a compromise temperature to produce reasonably a high proportion of ammonia in the equilibrium mixture in a very short time.

Which of the following catalyst is used in the Haber process for the manufacture of ammonia?

chemistry nitrogen and sulfur ammonia and fertilizers preparation of ammonia-laboratory method and haber's process ammonia

  1. Platinized asbestos

  2. Iron with a suitable promoter

  3. Copper oxide

  4. Alumina

Show answer
Correct Option: B
Explanation:

The Haber process, also called the Haber Bosch process, is the industrial implementation of the reaction of nitrogen gas and hydrogen gas. It is the main industrial procedure to produce ammonia and catalyst used is iron with a suitable  promoter like $K _2O$, $CaO$, $SiO _2$, and $Al _2O _3$.
Option B is correct.

Ammonia gas is not prepared by :

chemistry nitrogen and sulfur ammonia and fertilizers preparation of ammonia-laboratory method and haber's process ammonia

  1. reduction of sodium nitrite or sodium nitrate by the reaction of zinc dust and sodium hydroxide

  2. hydrolysis of calcium cyanamide

  3. heating ammonium chloride with slaked lime

  4. heating of $(NH _4) _2Cr _2O _7$

Show answer
Correct Option: D
Explanation:

(A) $NO _2^-+7[H]^-\xrightarrow {Zn/NaOH} NH _3+2H _2O; NO _3^-+9[H]^-\xrightarrow {Zn/NaOH} NH _3+3H _2O$
(B) $CaCN _2+3H _2O\rightarrow CaCO _3+2NH _3$
(C) $NH _4Cl+Ca(OH) _2\rightarrow 2NH _3+CaCl _2+2H _2O$
(D) $(NH _4) _2Cr _2O _7\rightarrow N _2+Cr _2O _3+4H _2O$

A solution of colorless salt H on boiling with excess NaOH produces a non-flammable gas. The gas evolution ceases after sometime upon addition of Zn dust to the same solution, the gas evolution restarts. The colourless salt(s) H is(are) :

chemistry nitrogen and sulfur ammonia and fertilizers preparation of ammonia-laboratory method and haber's process ammonia

  1. $NH _4NO _3$

  2. $NH _4NO _2$

  3. $NH _4Cl$

  4. $(NH _4) _2SO _4$

Show answer
Correct Option: A,B
Explanation:
Option (A), (B) are correct.
The colorless salt H is either $NH _4NO _3$ or $NH _4NO _2$. The colorless salt produces $NH _3$ gas (non-inflammable) on boiling with excess of $NaOH$. On addition of zinc dust (a reducing agent) to this solution, sodium nitrite or sodium nitrate will liberate $NH _3$ gas again.
 
$NH _4NO _3+ NaOH \longrightarrow NH _3+NaNO _3+H _2O$
$7NaOH+NaNO _3+4Zn\longrightarrow 4Na _2ZnO _2+NH _3+2H _2O$

$NH _4NO _2+NaOH \longrightarrow NaNO _2+NH _3+H _2O$
$3Zn+5NaOH+NaNO _2 \longrightarrow 3Na _2ZnO _2+NH _3$

Hydride of nitrogen is called :

chemistry nitrogen and sulfur ammonia and fertilizers preparation of ammonia-laboratory method and haber's process ammonia

  1. Hydrogen sulphide

  2. Water

  3. Ammonia

  4. Nitrous oxide

Show answer
Correct Option: C
Explanation:
Hydride of nitrogen is the binary compound formed by the combination of hydrogen and nitrogen .
The hydride formed with nitrogen is ammonia ($NH _3$).
Hence option C is correct.

In Haber process 30 litres of dihydrogen and 30 litres of dinitrogen were taken for reaction which yielded only 50% of the expected product. What will be the composition of gaseous mixture under the aforesaid condition in the end?

chemistry nitrogen and sulfur ammonia and fertilizers preparation of ammonia-laboratory method and haber's process ammonia

  1. 20 litres ammonia. 20 litres nitrogen, 20 litres hydrogen

  2. 10 litres ammonia, 25 litres nitrogen, 15 litres hydrogen

  3. 20 litres ammonia, 10 litres nitrogen, 30 litres hydrogen

  4. 20 litres ammonia, 25 litres nitrogen, 15 litres hydrogen

Show answer
Correct Option: B

In Haber process $30L$ of Dihydrogen and $30L$ of dinitrogen were taken for reaction which yielded only $50\% $of the expected product . what will be the composition of gaseous mixture under the aforesaid condition in the end?  

chemistry nitrogen and sulfur ammonia and fertilizers preparation of ammonia-laboratory method and haber's process ammonia

  1. $20L$ ammonia $10L$ nitrogen , $30L$ hydrogen

  2. $20L$ ammonia , $125L$ nitrogen , $25L$ ydrogen

  3. $20L$ ammonia , $20L$ nitrogen , $20L$hydrogen

  4. $10L$ ammonia , $25L$nitrogen , $15L$ hydrogen

Show answer
Correct Option: D