Tag: preparation of gases

Questions Related to preparation of gases

Among the following compounds, which on heating do not produce ${N _2}$?

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

  1. (${NH _4}) _2 Cr _2 O _7$

  2. ${NH _4 Cl +Na NO _2}$

  3. ${NH _4 Cl+Ca O}$

  4. ${Ba(N _3) _2}$

Show answer
Correct Option: C
Explanation:

(NH$ _4$)$ _2$Cr$ _2$O$ _7$ $\rightarrow$ N$ _2$ + Cr$ _2$O$ _3$ + H$ _2$O

NH$ _4$Cl + NaNO$ _2$ $\rightarrow$ N$ _2$ + H$ _2$O + NaCl

2 NH$ _4$Cl + CaO $\rightarrow$ 2 NH$ _3$ + CaCl$ _2$ + H$ _2$O

Ba(N$ _3$)$ _2$ $\xrightarrow{\text{heat}}$ Ba + 3N$ _2$

Thus, 2 NH$ _4$Cl + CaO will not produce N$ _2$.

Hence, the correct option is $\text{C}$

Select the correct statement. 

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

  1. Mixture of $NH _4Cl$ and $NaNO _2$ on heating gives $N _2$ gas

  2. $CFC$ is used as refrigerating fluid and as propellant in aerosols

  3. Phosgene is formed when $P _4$ reacts with $NaOH$

  4. Phosgene dissolves in water forming $P _2O _5$

Show answer
Correct Option: A

Nitrogen is obtained by the thermal decomposition of :

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

  1. $NH _4NO _2$

  2. $NH _4NO _3$

  3. $AgNO _3$

  4. $Pb(NO _3) _3$

Show answer
Correct Option: A
Explanation:

Reactions are:

$NH _4NO _3\rightarrow N _2O+H _2O$

$NH _4NO _2\rightarrow N _2+H _2O$

$AgNO _3\rightarrow Ag+NO _2+1/2O _2$

So, nitrogen is obtained from $NH _4NO _2$

Which one of the following pairs is obtained on heating ammonium dichromate?

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

  1. $N _2$ and $H _2$O

  2. $H _2$O and $H _2$O

  3. $NO _2$ and $H _2$O

  4. NO and $NO _2$

Show answer
Correct Option: A
Explanation:
On heating ammonium dichromate; $N _2$,$H _2O$ and $Cr _2O _3$ are formed.
 
$(NH _4) _2Cr _2O _7 (s) \longrightarrow N _2 (g) + 4H _2O (g) + Cr _2O _3 (s)  \Delta H = -429 kcal/mol$

Option (A) is correct.

On heating ammonium dichromate, the gas evolved is:

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

  1. oxygen.

  2. ammonia.

  3. nitrous oxide.

  4. nitrogen.

Show answer
Correct Option: D
Explanation:

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


Ammonium dichromate decomposes on heating to produce nitrogen gas water vapour (gaseous due to the temperature of the reaction), and solid chromium(III) oxide.

$(NH _4) _2Cr _2O _7$ on heating liberates gas. The same gas will be obtained by :

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

  1. heating $NH _4NO _2$

  2. heating $NH _4NO _3$

  3. treating $Mg _3N _2$ with $H _2O$

  4. heating $H _2O _2$ on $NaN0 _2$

Show answer
Correct Option: A
Explanation:
On heating, $(NH _{4}) _{2}Cr _{2}O _{7}$ gives, nitrogen gas. 

$(NH _{4}) _{2}Cr _{2}O _{7}\rightarrow N _{2}+Cr _{2}O _{3}+4H _{2}O$
          (Orange)                                 (Green)

But whenever, $NH _4NO _2$ and $NH _4NO _3$ heated, then nitrogen and nitrogen dioxide gas liberated.

$NH _{4}NO _{2}\rightarrow N _{2}+2H _{2}O$

$NH _{4}NO _{3}\rightarrow N _{2}O+2H _{2}O$

So, the correct option is $A$

The products formed when an aqueous solution of hydrazine reacts with an aqueous alkaline solution of potassium ferricyanide are:

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

  1. ${K} _{4}[Fe{(CN)} _{6}]$ and ${H} _{2}$.

  2. $4{K} _{4}[Fe{(CN)} _{6}]+4H _2O$ and ${N} _{2}$.

  3. $4{K} _{4}[Fe{(CN)} _{6}]$ and ${H} _{2}$.

  4. none of these

Show answer
Correct Option: B
Explanation:

$4{K} _{3}[Fe{(CN)} _{6}]+4KOH+{N} _{2}{H} _{4}\longrightarrow 4{K} _{4}[Fe{(CN)} _{6}]+4{H} _{2}O+{N} _{2}$.

Hence, the given statement is false.

Complete the given reaction :


${(NH _4)} _2Cr _2O _7  \longrightarrow$

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

  1.  $3N _2+ 4H _2O+ 2Cr _2O _3$

  2. $N _2+ 3H _2O+ Cr _2O _3$

  3. $N _2 + 4H _2O+ Cr _2O _3$

  4. $4N _2+ 4H _2O+ Cr _2O _3$

Show answer
Correct Option: C

Which of the following on heating will not evolve N$ _2$ gas?

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

  1. NH$ _{3}$ + NaNO$ _{2}$

  2. NH$ _{4}$Cl + NaNO$ _{2}$

  3. N$ _{2}$O + Cu

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

Show answer
Correct Option: A
Explanation:

The given reactions take place as:


$NH _3 + NaNO _2 \rightarrow NH _3NO _2 + Na$


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

$N _2O +Cu \rightarrow N _2 + CuO$

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



Hence, the reaction between ammonia and sodium nitrate do not evolve $N _2$ gas. 

Thus option A is the correct answer.

$Mg _3N _2 \xrightarrow{H _2O} A(gas) \xrightarrow[\triangle]{CuO} B + C(g) + H _2O$
$C(g)$ can be obtained by heating:

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

  1. $(NH _4) _2SO _4$

  2. $(NH _4) _2Cr _2O _7$

  3. $NH _4NO _3$

  4. $NH _4Cl$

Show answer
Correct Option: B
Explanation:

$Mg _3N _2 \xrightarrow []{3H _2O} \underset {(A)}{2NH _3}+3MgO$

$NH _3 \xrightarrow []{CuO} \underset {(C)}{N _2}(g)+\underset {(B)}{Cu}+H _2O$
$N _2$ will be obtained by decomposition of Ammonium dichromate.
$(NH _4) _2Cr _2O _7 (s) \longrightarrow Cr _2O _3(g)+\underset {(C)}{N _2}+4H _2O$ .