Chemistry Test - 10

The defects in which the stoichiometry of a crystal is not affected, are called stoichiometric defects. Thus, in such defects, the ratio of positive and negative ions are the same as indicated by a chemical formula of the compound. The compounds in which the number of positive and negative ions are exactly in the ratios indicated by their chemical formulae are called stoichiometric compounds. The defects that do not disturb the stoichiometry (the ratio of numbers of positive and negative ions) are called stoichiometric defects.

A student slowly mixes salt into 25 ml of water until no more salt dissolves in it. The student could make more salt dissolve in the solution by heating it.

• As no more salt is dissolving in the solution, the solution has became saturated solution.
• The student can dissolve more solution by heating the solution as on heating the saturated solution become supersaturated.
• After, the solution become supersaturated, no more salt can be dissolved, it will precipitate out.

Given:-

Time \((t)=10 \min\)

\(=10 \times 60\)

\(=600 {~s}\)

Current passed \(({i})=0.75 {~A}\)

From Faraday's law of electrolysis, \({q}={n F}\)

Whereas, \(n\) is the no. of moles of electrons used

\(\Rightarrow {i} \times {t}={n} {F}(\because {q}={I} \times {t})\)

\(\Rightarrow {n}=\frac{{i} \times {t}}{{F}}\)

\(\Rightarrow {n}=\frac{0.75 \times 600}{96500}=\frac{4.5}{965} {~mol}\)

Now, \({H}_{2} {O} \longrightarrow 4 {H}^{+}+{O}_{2}+4 {e}^{-}\)

Amount of \({O}_{2}\) released at STP when \(4\) mole of electrons are used \(=22400 {~mL}\)

Amount of \({O}_{2}\) released at STP when \(\frac{4.5}{965}\) mole of electrons are used \(=\frac{22400}{4}\) \(× (\frac{4.5}{965})\)

\(=\) \(26.11 {~mL}\)

Hence the volume of oxygen liberated at the anode (at STP) will be \(26.11 mL\).

Equanil is a tranquilizer.

• This medication is used short-term to treat symptoms of anxiety and nervousness.
• It acts on certain centers of the brain to help calm your nervous system which is same as tranquilizer which also have a calming effect and eliminate both the physical and psychological effects on anxiety or fear.

Effect of temperature on the rate of reaction hence, rate constant \(k\), can be calculated by using Arrhenius equation which is \(K=A e^{-E_{a} / R T}\)

Given:

\(A=6.0 \times 10^{-14} s^{-1}\)

\(E_{a}=104.4 K J m o l^{-1}\)

\(T=\infty\)

\(\because K=e^{\frac{-E_{a}}{R T}}\)

or \(\log K=\log A-\frac{E_{a}}{2.303 R T}\)

At \(T=\infty\)

\(\log k-\log A+\frac{E_{a}}{2.303 R \times 100}\)

\(\log k=\log A+0\)

\(\log k=\log 6 \times 10^{14}\)

\(K=6 \times 10^{14} s^{-1}\)

Benzene and toulene will form an ideal solution.

• The substances that have similar structures and polarities form nearly ideal solution.
• Since both benzene and toluene are non-polar, operating intermolecular forces are almost similar. Therefore, they form an ideal solution.
• An ideal solution is a homogeneous mixture of substances that has physical properties linearly related to its pure components or obeys Raoult’s law.

In the electrolytic method of obtaining aluminium from purified bauxite, cryolite is added to the charge because it reduces the melting point of Bauxite (from \(1200^{\circ} \mathrm{C}\) to \(800^{\circ}-900^{\circ} \mathrm{C}\) ) and also it increases the electrical conductivity of the mixture.

Palladium (Pd) does not belong to 3d series of transition elements (Atomic number of Pd is 42).

Palladium (Pd) belongs to the 4d series which contain elements from Yttrium (Y) to Cadmium (Cd).

The d-block elements are called transition elements.

They are called d-block as their valency electrons enter the d-orbital.

\(4 \mathrm{d}^{10} 5 \mathrm{s}^{2}\) is the exceptional configuration of Pd. Its electronic configuration should be \([36 \mathrm{Kr}] 4 \mathrm{d}^{8} 5 \mathrm{s}^{2}\)

Thus, its Period \(=5\)th (Highest orbit) Group \(=\mathrm{ns}+(\mathrm{n}-1) \mathrm{d}\) electrons

\(=2+8=10\)

As we know,

\(E_{n}=\frac{(-13.595 \mathrm{eV}) Z^{2}}{n^{2}} \text { atom }^{-1}\)

Here \(n=1: Z=2\) for \({He}^{+}\)

\(\therefore E_{1}=\frac{-13.595 {eV} \times 4}{1^{2}}=-54.380 {eV}\)

Also we know,

\(r_{n}=\frac{(0.529 \mathring{\mathrm{A}}) n^{2}}{Z}\)

Here, \(n=1\) or \(Z=2\) for \({He}^{+}\)

\(\therefore r_{1}=\frac{0.529 \mathring{\mathrm{A}} \times 1^{2}}{2}=0.2645 \mathring{\mathrm{A}}\)

Grignard reagents form via the reaction of an alkyl or aryl halide with magnesium metal. The reaction is conducted by adding the organic halide to a suspension of magnesium in an ethereal solvent, which provides ligands required to stabilize the organomagnesium compound. The halide could also be all ( chlorine, bromine, iodine) except fluorine. It’s slightly easier to make Grignard from the iodides and bromides. The halide is that the “X” observed after we talk over Grignard reagents as \(" R M g X\) ".

The ether in the presence of which the reaction takes place is also called diethyl ether. It is synthesised by dehydration of ethanol using sulphuric acid.

The chemical action for the assembly of Grignard reagent is as follows:

\(R-X+M g \stackrel{\text { dryether }}{\longrightarrow} R-M g-X\) (Grignard reagent)