Given below are some nitrogen containing compounds.
Four amine candidates are indexed to find the optimal basic compound for reaction calculations.
Each of them is treated with HCl separately.
1.0 g of the most basic compound will consume ________ mg of HCl.
(Given molar mass in g mol ^-1$^{-1}$ C:12, H : 1, O : 16, Cl : 35.5)
Four amine candidates are indexed to find the optimal basic compound for reaction calculations.
Numerical Answer Type:
Enter a numerical valueAnswer: 341 to 341+4 marks
Solution & Explanation
### Related Formula
textMoles = fractextMasstextMolar Mass$$\text{Moles} = \frac{\text{Mass}}{\text{Molar Mass}}$$textMass of HCl consumed = n_textamine cdot M_textHCl$$\text{Mass of HCl consumed} = n_{\text{amine}} \cdot M_{\text{HCl}}$$
### Core Logic
Step 1: Identify the most basic amine
Benzylamine (mathrmC_6mathrmH_5mathrmCH_2mathrmNH_2$\mathrm{C}_6\mathrm{H}_5\mathrm{CH}_2\mathrm{NH}_2$) is the most basic compound here because its nitrogen lone pair is localized and not involved in aromatic resonance. This stands in contrast to aniline or amides, which delocalize their lone pairs into the ring or carbonyl group .
Step 2: Neutralization Stoichiometry
mathrmC_6H_5CH_2NH_2 + mathrmHCl
ightarrow mathrmC_6H_5CH_2NH_3^+ Cl^-$$\mathrm{C_6H_5CH_2NH_2} + \mathrm{HCl}
ightarrow \mathrm{C_6H_5CH_2NH_3^+ Cl^-}$$
Molar Mass of Benzylamine (mathrmC_7mathrmH_9mathrmN$\mathrm{C}_7\mathrm{H}_9\mathrm{N}$):
M = (7 cdot 12) + (9 cdot 1) + 14 = 84 + 9 + 14 = 107 \, mathrmg/mol$$M = (7 \cdot 12) + (9 \cdot 1) + 14 = 84 + 9 + 14 = 107 \, \mathrm{g/mol}$$
Moles of Benzylamine in 1.0text g$1.0\text{ g}$ :
n = frac1.0107 simeq 0.009346 \, mathrmmol$$n = \frac{1.0}{107} \simeq 0.009346 \, \mathrm{mol}$$
Since 1 mole of benzylamine reacts with 1 mole of mathrmHCl$\mathrm{HCl}$ :
textMoles of HCl consumed = 0.009346 \, mathrmmol$$\text{Moles of HCl consumed} = 0.009346 \, \mathrm{mol}$$textMass of HCl = 0.009346 cdot 36.5 = 0.3411 \, mathrmg = 341.1 \, mathrmmg
ightarrow 341$$\text{Mass of HCl} = 0.009346 \cdot 36.5 = 0.3411 \, \mathrm{g} = 341.1 \, \mathrm{mg}
ightarrow 341$$
### Pattern Recognition
Aliphatic localized clusters (like the -mathrmCH_2mathrmNH_2$-\mathrm{CH}_2\mathrm{NH}_2$ segment in benzylamine) always show higher basicity than aromatic ring-conjugated arrays.
### Evaluation Rubric / Model Answer
null
### Chapter Mix
Class 12 Chemistry: Amines
Four amine candidates are indexed to find the optimal basic compound for reaction calculations.
Q72jee_main_2024_30_jan_morningPreparation of Amines
The final product A, formed in the following multistep reaction sequence is:
The image outlines a synthesis pathway converting bromobenzene through several steps finally using Hoffmann bromamide reaction.
A.The image outlines a synthesis pathway converting bromobenzene through several steps finally using Hoffmann bromamide reaction.
B.The image outlines a synthesis pathway converting bromobenzene through several steps finally using Hoffmann bromamide reaction.
C.The image outlines a synthesis pathway converting bromobenzene through several steps finally using Hoffmann bromamide reaction.
D.The image outlines a synthesis pathway converting bromobenzene through several steps finally using Hoffmann bromamide reaction.
Solution
### Core Logic
Step 1: Bromobenzene + Mg, ether rightarrow Phenylmagnesium bromide$Mg, ether \rightarrow Phenylmagnesium bromide$ (Grignard reagent).
Step 2: Grignard + CO_2$CO_2$ followed by H^+ rightarrow Benzoic acid$H^+ \rightarrow Benzoic acid$ (C_6H_5COOH$C_6H_5COOH$).
Step 3: Benzoic acid + NH_3, Delta rightarrow Benzamide$NH_3, \Delta \rightarrow Benzamide$ (C_6H_5CONH_2$C_6H_5CONH_2$).
Step 4: Benzamide + Br_2/NaOH$Br_2/NaOH$ (Hoffmann bromamide degradation) rightarrow Aniline$\rightarrow Aniline$ (C_6H_5NH_2$C_6H_5NH_2$).
The image outlines a synthesis pathway converting bromobenzene through several steps finally using Hoffmann bromamide reaction.
### Step 1: Tracing the product
The final product 'A' is Aniline.
### Evaluation Rubric / Model Answer
null
### Chapter Mix
Class 12 Chemistry: Amines
Class 12 Chemistry: Aldehydes, Ketones and Carboxylic Acids
Class 12 Chemistry: Haloalkanes and Haloarenes
Q78jee_main_2024_30_jan_morningChemical Reactions of Amines
Following is a confirmatory test for aromatic primary amines. Identify reagent (A) and (B)
Ph-NH_2 xrightarrowA Ph-N_2^+Cl^- xrightarrowB textScarlet red dye$Ph-NH_2 \xrightarrow{A} Ph-N_2^+Cl^- \xrightarrow{B} \text{Scarlet red dye}$
### Core Logic
The reaction sequence represents the classic dye test for aromatic primary amines.
Step 1 (Diazotization): Aniline (Ph-NH_2$Ph-NH_2$) reacts with nitrous acid (generated in situ from NaNO_2 + HCl$NaNO_2 + HCl$) at low temperature (0-5^circ C$0-5^\circ C$) to form benzene diazonium chloride (Ph-N_2^+Cl^-$Ph-N_2^+Cl^-$).
Thus, Reagent A is NaNO_2 + HCl$NaNO_2 + HCl$ at 0-5^circ C$0-5^\circ C$.
### Step 2: Coupling Reaction
Step 2: The diazonium salt undergoes an electrophilic substitution (coupling reaction) with an electron-rich aromatic ring to form an azo dye.
The formation of a 'scarlet red dye' is specifically the result of coupling benzene diazonium chloride with beta$\beta$-naphthol in a weakly basic medium (NaOH).
Chemical Reactions of Amines solution diagram for Q78 - JEE Main 2024 Morning
### Evaluation Rubric / Model Answer
null
### Chapter Mix
Class 12 Chemistry: Amines
Q69jee_main_2024_31_jan_eveningReactions of Diazonium Salts
The azo-dye (Y) formed in the following reactions is
textSulphanilic acid + NaNO_2 + CH_3COOH rightarrow X$\text{Sulphanilic acid } + NaNO_2 + CH_3COOH \rightarrow X$The image shows the reaction of intermediate X with N,N-dimethylaniline to form an azo dye (Y).
### Core Logic
1) Sulphanilic acid reacts with NaNO_2$NaNO_2$ and CH_3COOH$CH_3COOH$ to form a diazonium salt (X).
2) The diazonium salt (X) then reacts with N,N-dimethylaniline (given in the coupling step image). The coupling takes place at the para position of the highly activated N,N-dimethylaniline ring.
3) This coupling yields Methyl Orange, an azo dye. Its structure is p$p$-dimethylaminoazobenzenesulphonic acid.
The image shows the reaction of intermediate X with N,N-dimethylaniline to form an azo dye (Y).
### Step 1: Final Identification
The final product (Y) matches option (4) structurally, containing the sulphonic acid group on one ring, the azo linkage, and the N,N-dimethylamine group on the para position of the other ring.
### Evaluation Rubric / Model Answer
null
### Chapter Mix
Class 12 Chemistry: Amines
Q70jee_main_2024_31_jan_eveningChemical Reactions of Amines
Given below are two statements:
Statement I: Aniline reacts with con. H_2SO_4$H_2SO_4$ followed by heating at 453-473 K gives p-aminobenzene sulphonic acid, which gives blood red colour in the 'Lassaigne's test'.
Statement II: In Friedel-Crafts alkylation and acylation reactions, aniline forms salt with the AlCl_3$AlCl_3$ catalyst. Due to this, nitrogen of aniline acquires a positive charge and acts as deactivating group.
In the light of the above statements, choose the correct answer from the options given below:
A.text(1) Statement I is false but statement II is true$\text{(1) Statement I is false but statement II is true}$
B.text(2) Both statement I and statement II are false$\text{(2) Both statement I and statement II are false}$
C.text(3) Statement I is true but statement II is false$\text{(3) Statement I is true but statement II is false}$
D.text(4) Both statement I and statement II are true$\text{(4) Both statement I and statement II are true}$
Solution
### Core Logic
Statement I: Aniline reacting with concentrated H_2SO_4$H_2SO_4$ gives anilinium hydrogensulphate, which on heating at 453-473 K produces sulphanilic acid (p-aminobenzene sulphonic acid). Because sulphanilic acid contains both Nitrogen and Sulphur, it gives a blood-red colouration in Lassaigne's test due to the formation of thiocyanate ion SCN^-$SCN^-$ which reacts with Fe^3+$Fe^{3+}$ to form [Fe(SCN)]^2+$[Fe(SCN)]^{2+}$. Thus, Statement I is true.
Statement II: In Friedel-Crafts reactions, the Lewis acid catalyst AlCl_3$AlCl_3$ reacts with the lone pair on the nitrogen atom of aniline to form a salt. This generates a positive charge on the nitrogen, transforming the -NH_2$-NH_2$ group from a strong activating group into a strong deactivating group, thus preventing the Friedel-Crafts reaction from occurring. Thus, Statement II is true.
Chemical Reactions of Amines diagram for Q70 - JEE Main 2024 Evening
### Step 1: Final Conclusion
Both Statement I and Statement II are true. Option (4) is correct.
### Evaluation Rubric / Model Answer
null
### Chapter Mix
Class 12 Chemistry: Amines
Class 11 Chemistry: Organic Chemistry - Some Basic Principles and Techniques
Q83jee_main_2024_31_jan_eveningAcylation of Amines
A compound (x) with molar mass 108mathrm~g\,mol^-1$108\mathrm{~g\,mol^{-1}}$ undergoes acetylation to give product with molar mass 192mathrm~g\,mol^-1$192\mathrm{~g\,mol^{-1}}$. The number of amino groups in the compound (x) is ________.
Numerical Answer.Answer: 2 to 2
Solution
### Related Formula
R-NH_2 + CH_3COCl rightarrow R-NH-COCH_3 + HCl$$R-NH_2 + CH_3COCl \rightarrow R-NH-COCH_3 + HCl$$
### Core Logic
During the acetylation of an amino group, one hydrogen atom (mass = 1text g/mol$1\text{ g/mol}$) is replaced by an acetyl group (-COCH_3$-COCH_3$, mass = 43text g/mol$43\text{ g/mol}$).
Gain in molecular weight for every one -NH_2$-NH_2$ group acetylated = 43 - 1 = 42text g/mol$43 - 1 = 42\text{ g/mol}$.
### Step 1: Calculating Number of Groups
Total increase in molecular weight = Final mass - Initial mass = 192 - 108 = 84text g/mol$192 - 108 = 84\text{ g/mol}$.
textNumber of amino groups = fractextTotal mass increasetextMass increase per group = frac8442 = 2$$\text{Number of amino groups} = \frac{\text{Total mass increase}}{\text{Mass increase per group}} = \frac{84}{42} = 2$$
### Evaluation Rubric / Model Answer
null
### Chapter Mix
Class 12 Chemistry: Amines
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