Chemistry Test - 9

Disulphide bridges stabilize tertiary structure. Primary structure is the sequence of amino acids in a polypeptide chain. Secondary structure is defined as the localized folding patterns of the polypeptide chain that are stabilized by hydrogen bonds.

Phenol is acidic in nature because it liberates the acidic proton easily and the conjugate base is also resonance stabilized.

and

• When the Chloride group is introduced at the para position, it Has a -I effect towards the ring. Also, the +R effects operate at the ortho and para positions.
• We know that -I of Cl is dominating and hence it helps in increasing the overall acidity of phenol.
• But, the -R effect of the nitro group dominates the -I of chlorine making nitro phenols more acidic than chlorophenols.

Comparison between

and

In the case of ortho nitrophenol, the negative charge is delocalized by -R of the nitro group.

But -R does not operate in the case of meta nitrophenol and thus it is less acidic than ortho nitrophenol.

Comparison between:

and

• There exists an intramolecular H bonding in ortho nitrophenol which makes the release of proton much more difficult.

Thus, the most acidic compound is .

Primary aliphatic amines with \(\mathrm{HNO}_2\) ( Nitrous acid)-

Primary amines react with \(\mathrm{HNO}_2\) and give a very unstable diazonium alkyl ion in form of alkyl diazonium salt, not even stable enough to isolate and it decomposes very rapidly in the product with the evolution of nitrogen gas.

Chemical reaction-

\(\mathrm{R}-\mathrm{NH}_2 \overset{{\mathrm{HONO}, \mathrm{HCl}, \Delta}}{\longrightarrow} \quad R-\mathrm{N}^{+} \equiv N \stackrel{\text { immediately }}{\longrightarrow} \mathrm{R}^{+}+\mathrm{N} 2\)

\(\mathrm{R}^{+} \stackrel{\mathrm{H}_2 \mathrm{O}, \Delta}{\longrightarrow} \mathrm{R}-\mathrm{OH}\)

Primary aromatic amines with \(\mathrm{HNO}_2\) - Primary aromatic amines form arenediazonium salts which are stable for a short time in solution at low temperatures (273-278 K). At higher temperatures the diazonium salt formed is unstable.

Chemical reaction-

\(\mathrm{Ar}-\mathrm{NH}_2 \stackrel{\mathrm{HONO}, \mathrm{HCl}, \Delta}{\longrightarrow} \quad A r-N^{+} \equiv \mathrm{NCl}^{-}\)(stable aromatic diazonium salt at low temperature)

\(\mathrm{Ar}-\mathrm{N}^{+} \equiv \mathrm{NCl}^{-} \stackrel{\mathrm{H}_2 \mathrm{O}, \Delta}{\longrightarrow} \mathrm{Ar}-\mathrm{OH}+\mathrm{N}_2 \uparrow\)

\(\mathrm{PbCl}_{4}\) exists but \(\mathrm{PbBr}_{4}\) and \(\mathrm{PbI}_{4}\) do not because \(\mathrm{Pb}-\mathrm{I}\) and \(\mathrm{Pb}-\mathrm{Br}\) bonds initially formed during the reaction do not release enough energy to unpair \(6 \mathrm{~s}^{2}\) electrons and excite one of them to higher orbital to have four unpaired electrons around lead atom. So, bromine and iodine are unable to oxidise \(\mathrm{Pb}^{2+}\) to \(\mathrm{Pb}^{4+}\).

Benzyl chloride gives benzoic acid on oxidation.

The reaction takes place as follows:

\(\mathrm{C}_{6} \mathrm{H}_{5} \mathrm{CH}_{2} \mathrm{Cl}+2 \mathrm{KOH}+2[\mathrm{O}] \longrightarrow \mathrm{C}_{6} \mathrm{H}_{5} \mathrm{COOK}+\mathrm{KCl}+\mathrm{H}_{2} \mathrm{O}\)

Moles \(=\) Molarity \(\times\) Volume \(=2.0 \times 0.150 \mathrm{~L}=0.300\)

Therefore, Mass of \(\mathrm{CH}_{3} \mathrm{OH}\) required \(=\) Moles \(\times\) Molar mass \(=\)

\(0.300 \mathrm{~mol} \times 32.0424 \mathrm{~g} / \mathrm{mol}=9.6 \mathrm{~g}\)

The halogen which is most reactive in the halogenation of alkanes in sunlight is Fluorine.

The order of reactivity of halogens towards the alkanes are in the order:

Fluorine > Chlorine > Bromine > Iodine.

Disproportionation reaction are the reactions in which the same element/compound get oxidized and reduced simultaneously.

The reactions are as follows:

(I) \(\left.2 \mathrm{Cu}^{+1} \rightarrow \mathrm{Cu}^{+2}+ \mathrm{Cu}^{0}\right\}\) Disproportionation

(II) \(\left.3 \mathrm{MnO}_{4}^{2-}+4 \mathrm{H}^{+} \rightarrow 2 \mathrm{MnO}_{4}^{-}+\mathrm{MnO}_{2}+2 \mathrm{H}_{2} \mathrm{O}\right\}\) Disproportionation

(III) \(\left.2 \mathrm{KMnO}_{4} \stackrel{\Delta}{\longrightarrow} \mathrm{K}_{2} \mathrm{MnO}_{4}+\mathrm{MnO}_{2}+\mathrm{O}_{2}^{+6}\right\}\) Not a Disproportionation

(IV) \(\left.2 \mathrm{MnO}_{4}^{-}+3 \mathrm{Mn}^{+2}+2 \mathrm{H}_{2} \mathrm{O} \rightarrow 5 \mathrm{MnO}_{2}+4 \mathrm{H}^{+}\right\}\) Not a Disproportionation

The correct name of \(\left[ Pt \left( NH _{3}\right)_{4} Cl _{2}\right]\left[ P tCl _{4}\right]\) is: Tetraaminedichloro platinum (IV) tetrachloro platinate(II)

First, we have to write the cationic part, of the coordinate compound

Here, the ligands are Amine and Chloride. Since there are 4 amine groups we'll name it as tetramine and 2 chloride groups will be named as dichloro. Also, we have platinum metal as the central metal atom in a cation, and it's oxidation state is +4 .

Now for the other (anionic part):

Here the ligand is chloride. Since there are 4 chlorides so we'll call it tetrachloride. We have the central metal atom as platinum again, but since it is in the anionic coordination sphere.

In physisorption adsorbent does not show specificity for any particular gas because involved Van der Waals forces are universal.

This phenomenon involves the use of weak Van der Waal forces by means of which gas molecules get adsorbed on a solid surface.There is no specificity as any gas can be adsorbed onto the surface.

During the charging of the lead storage battery, the sulphuric acid is regenerated.

• Sulphuric acid acts as an electrolyte in lead storage batteries.
• Thus, lead storage batteries can be used again and again by regenerating the sulphuric acid.

A few elements like carbon, sulphur, gold, and noble gases, occur in the free state while others are found in combined forms in the earth’s crust.

Elements vary in abundance. Among metals, aluminium is the most abundant. Iron is the second most abundant metal in the earth’s crust. It forms a variety of compounds and their various uses make it a very important element. It is one of the essential elements in biological systems as well.

\(\mathrm{Fe}\) and \(Z n\) is not available in both combined and native state.

Structural formula of Haloalkane isR-X.

It was derived fromalkanescontaining a halogens or more.

They are used as flame retardants, fire extinguishers, refrigerants, propellants, solvents, and medicinal items.

"RX"in which R is an alkyl or alkyl substituted group and X is a halogen (F, Cl, Br, I).

Haloalkanesare commonly used in organic synthesis as synthonous alternatives to alkyl cation (R+).

When the gas is not highly soluble in this case is Henry's law valid.

The law is only valid when the molecules in the system are in equilibrium. When the gases are under extremely high pressure, Henry's Law does not apply. This law also does not apply when the solution and gas are involved in a chemical reaction with each other.

Given that:

Resistance, \((R)=3.16 \Omega\)

Cell constant \(=0.367 \mathrm{~cm}^{-1}\)

We know that:

Conductance, \((C)=\frac{1}{R}\)

\(=\frac{1}{3.16 \mathrm{ohm}}\)

\(=0.0316 \mathrm{~ohm}^{-1}\)

Specific conductance, \((\mathrm{\kappa}) =\) Conductance \(\times\) cell constant

\(=0.0316 \mathrm{~ohm}^{-1} \times 0.367 \mathrm{~cm}^{-1}\)

\(=0.0116 \mathrm{~ohm}^{-1} \mathrm{cm}^{-1}\)