Tag: preparation of gases

Questions Related to preparation of gases

Pure ${N} _{2}$ gas is obtained from:

chemistry preparation of gases nitrogen gas component of air - nitrogen nitrogen

  1. $NH _3 +  NaNO _2$

  2. $Ba(N _{3}) _{2}$

  3. $N _2O + Cu$

  4. $(NH _4) _2Cr _2O _7$

Show answer
Correct Option: B
Explanation:

Heating $Ba(N _3) _2$ we get pure $N _2$


$Ba(N _{3} ) _{2} \rightarrow Ba + 3N _{2} $

Hence, option B is correct.

Which of the following compounds does not give $N _2$ when heated?

chemistry preparation of gases nitrogen gas component of air - nitrogen nitrogen

  1. $NH _4NO _2$

  2. $NH _4NO _3$

  3. $NaN _3$

  4. Both A and B

Show answer
Correct Option: B
Explanation:

$(1)NH _4NO _2\overset{\Delta }{\rightarrow}N _2+2H _2O$
$(2)NH _4NO _3\overset{\Delta }{\rightarrow}N _2O+2H _2O$
$(3)2NaN _3\overset{\Delta }{\rightarrow}3N _2+2Na$

What is obtained when ammonium dichromate is heated?

chemistry preparation of gases nitrogen gas component of air - nitrogen nitrogen

  1. Nitrogen

  2. Oxygen

  3. Ammonia

  4. None of the above

Show answer
Correct Option: A
Explanation:

$(NH _4) _2 Cr _2O _7 \overset{\Delta}{\rightarrow}N _2 + 4H _2O+Cr _2O _3$

Pure $N _2$ gas is obtained from:

chemistry preparation of gases nitrogen gas component of air - nitrogen nitrogen

  1. $NH _3+NaNO _2$

  2. $NH _4Cl+NaNO _2$

  3. $N _2O+Ca$

  4. $(NH _4) _2Cr _2O _7$

Show answer
Correct Option: B
Explanation:

Pure $N _2$ gas is obtained when $NH _4Cl+ NaNO _2$ is reacted.

$NH _4Cl+ NaNO _2\rightarrow N _2 + 2 H _2O + NaCl$

Hence option B is correct.

Pure $N {2}$ can be obtained by heating_______.

chemistry preparation of gases nitrogen gas component of air - nitrogen nitrogen

  1. $NH _{3}$ with $CuO$

  2. $NH _{4}NO _{3}$

  3. $(NH _{4}) _{2}Cr _{2}O _{7}$

  4. $Ba(N _{3}) _{2}$

Show answer
Correct Option: D
Explanation:

Barium azide can also be used in the preparation of extra pure nitrogen on heating.
$Ba(N _3) _2 \rightarrow Ba + 3N _2$

$NH _4NO _3$ and $NH _4NO _2$ on heating decomposes into :

chemistry preparation of gases nitrogen gas component of air - nitrogen nitrogen

  1. $NO _2, N _2$

  2. $NO _2, NO _3$

  3. $N _2O, N _2$

  4. $NO _3, NO _2$

Show answer
Correct Option: C
Explanation:

Reaction:
$NH _4NO _3\overset{\triangle}{\longrightarrow} N _2O + 2H _2O$
$NH _4NO _2 \overset{\triangle}{\longrightarrow} N _2 + 2H _2O$

In the reaction,

${ \left( { NH } _{ 4 } \right)  } _{ 2 }{ Cr } _{ 2 }{ O } _{ 7 }\xrightarrow [  ]{ \Delta  } { N } _{ 2 }+{ H } _{ 2 }O+{ Cr } _{ 2 }{ O } _{ 3 }$

The coefficient of ${H} _{2}O$ is :

chemistry preparation of gases nitrogen gas component of air - nitrogen nitrogen

  1. $1$

  2. $2$

  3. $3$

  4. $4$

Show answer
Correct Option: D
Explanation:

$ (NH _4) _2Cr _2O _7(s) \rightarrow N _2(g) + 4 H _2O(g) + Cr _2O _3(s)$


To balance the reaction we require 4 moles of $H _2O$.

Hence option D is correct.

Density of nitrogen gas prepared from air is slightly greater than that of nitrogen prepared by chemical reaction from a compound of nitrogen, because aerial nitrogen contains: 

chemistry preparation of gases nitrogen gas component of air - nitrogen nitrogen

  1. $CO _2$

  2. Argon

  3. some $N _2$ molecules analogous to $O _2$

  4. greater amount of $N _2$ molecules derived from $N-15$ isotope

Show answer
Correct Option: D
Explanation:

The density of nitrogen gas prepared from the air is slightly greater than that of nitrogen prepared by chemical reaction from a compound of nitrogen, because aerial nitrogen contains a greater amount of $\displaystyle N _2$ molecules derived from $\displaystyle N-15$ isotope.
Note: Molecules containing $\displaystyle N-15$ isotope are heavier than molecules containing$\displaystyle N-14$ isotope as N atom has more number of neutrons.

Which of the following gives nitrogen on thermal decomposition?

chemistry preparation of gases nitrogen gas component of air - nitrogen nitrogen

  1. Ammonium nitrite

  2. Ammonia

  3. Ammonium dichromate

  4. Air

Show answer
Correct Option: A,C
Explanation:

$ { { (NH } _{ 2 }) } _{ 2 }{ Cr } _{ 2 }{ O } _{ 7 }\xrightarrow [ thermal\quad decomposition ]{ \Delta  } { Cr } _{ 2 }{ O } _{ 3 }+{ N } _{ 2 }+4{ H } _{ 2 }O\ N{ H } _{ 4 }{ NO } _{ 2 }\xrightarrow [ thermal\quad decomposition ]{ \Delta  } { N } _{ 2 }+2{ H } _{ 2 }O $

Ammonium nitrite and Ammonium dichromate both give nitrogen on thermal decomposition.