Tag: study of aluminium chloride

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Multiple choice chemistry p- block elements-i study of aluminium chloride study of aluminium structure of some compounds

 ${ AlF } _{ 3 }$ is soluble in $HF$ only in presence of $KF$. It is due to the formation of:

  1. ${ AlH } _{ 3 }$
  2. ${ K[AlF } _{ 3 }H]$
  3. ${ { K } _{ 3 }[AlF } _{ 3 }{ H } _{ 3 }]$
  4. ${ { K } _{ 3 }[AlF } _{ 6 }]$
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation
$AlF _3$  is insoluble in the anhydrous $HF$ because the $F^-$ ions are not available in intermolecular hydrogen bonded HF, but it becomes soluble in the presence of $KF$ due to the formation of soluble complex, $K _3[AlF _6].$
$AlF _3+3KF⟶K _3[AlF _6]$
Hence option D is correct answer.
Multiple choice chemistry p- block elements-i study of aluminium chloride study of aluminium structure of some compounds

The molecule which is NOT hydrolysed by water at $25^oC$ is

  1. $AICI _3$
  2. $SiCI _4$
  3. $BF _3$
  4. $SF _6$
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Silicon tetrachloride, boron trifluoride, and aluminium chloride all readily undergo hydrolysis due to vacant d-orbitals or electron deficiency allowing water molecules to coordinate. Sulfur hexafluoride is sterically hindered and lacks accessible coordination sites, making it inert to water at room temperature.

Multiple choice chemistry p- block elements-i study of aluminium chloride study of aluminium structure of some compounds

${Al} _{2}{O} _{3}$ is reduced by electrolysis at low potential and high currents. If $4.0\times {10}^{4}$ amperes of current is passed through molten ${Al} _{2}{O} _{3}$ for 6 hours, what mass of aluminium is produced? (Assume 100% current efficiency, At. mass of $Al=27g{mol}^{-1}$)

  1. $1.3\times {10}^{4}g$
  2. $9.0\times {10}^{3}g$
  3. $8.1\times {10}^{4}g$
  4. $2.4\times {10}^{5}g$
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

$Al _2O _3(l) \rightarrow2Al^{3+}(l) + 3O^{2-}(l) $

Reduction equation of $Al^{3+}: $
$Al^{3+}(aq) + 3e^- \rightarrow Al(s) $

As,

Ampere = Coulomb / sec 

Time unit should be second. 
$6 hr \times 60 \dfrac{min}{ hr} \times 60 \dfrac{sec}{ min} = 21600 sec $
Coulomb = Ampere x second $= 40000 \times 21600 = 8.64\times10^8 $

1 mol $e^-$ carries a charge of 1 faraday, or 96485 coulombs. 
Then the mole of $e^-$ used in the electrolysis will be: 

$\dfrac{8.64\times10^8   \text{coulombs}}{ 96485 -\text{coulombs/mol}}- of -e^- = 8954.8  \text{mol of} -e^- $

According to the reduction equation, 3 moles of e- are needed to reduce 1 mol of Al^3+ to Al metal. 
Then , the mole of Al to be deposited at the cathode will be; 
$\dfrac{8954.8 \text{mol e-} }{ \dfrac{3 -\text{mol of e-}}{\text{mol Al}}} = 2985\text{ mol Al} $

Molar mass of $Al : 26.98 g/mol $
Mass of Al produced$: 2985 mol \times 26.98 g/mol = 80535 g $
$Al = 8.1\times10^4 g$

Multiple choice chemistry p- block elements-i study of aluminium chloride study of aluminium structure of some compounds

Alluminium chloride nexists as dimer, $A{l _2}C{l _6}$ in solid state as well as in solution of non-polar solvents such as benzene. When dissolved in water, it gives:

  1. ${{\text{[Al(OH}}{{\text{)}} _{\text{6}}}{\text{]}}^{{\text{3 - }}}}{\text{ + 3HCl}}$
  2. ${{\text{[Al(}}{{\text{H}} _2}{\text{O}}{{\text{)}} _{\text{6}}}{\text{]}}^{{\text{3 + }}}}{\text{ + 3HC}}{{\text{l}}^ - }$
  3. $A{l^{3 + }} + 3C{l^ - }$
  4. ${\text{A}}{{\text{l}} _{\text{2}}}{{\text{O}} _{\text{3}}}{\text{ + 6HCl}}$
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

When anhydrous aluminum chloride dissolves in water, it undergoes hydration to form the hexaaquaaluminum(III) ion, [Al(H2O)6]3+, and releases chloride ions into the solution.

Multiple choice chemistry p- block elements-i study of aluminium chloride study of aluminium structure of some compounds

Aluminium chloride exists as dimer, $Al _2Cl _6$, in solid state as well as in solution of non-polar solvents such as $C _6H _6$.


 When dissolved in water it gives :

  1. $Al _2O _3+6HCl$
  2. $[Al(H _2O) _6]^{3+}+3Cl^-$
  3. $[Al(OH) _6]^{3+}+6Cl^-$
  4. $Al^{3+}+3Cl^-$
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Reaction:

$AlCl _3 $ is covalent but in water it becomes ionic due to large hydration energy oh $Al^{3+}$.

$AlCl _3 + 6H _2O \rightarrow [Al(H _2O) _6]^{3+} + 3Cl^-$.


Hence,option B is correct.

Multiple choice chemistry p- block elements-i study of aluminium chloride study of aluminium structure of some compounds

Aqueous solution of $AIC{I _3}$ on heating to dryness will give 

  1. $AIC{I _3}$
  2. $A{l _2}{O _3}$
  3. $Al(OH)C{L _2}\,$
  4. $A{L _2}C{l _6}$
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Heating an aqueous solution of AlCl3 causes hydrolysis where the aluminum ion reacts with water to form aluminum hydroxide, which then dehydrates to aluminum oxide (Al2O3) upon heating to dryness.

Multiple choice chemistry p- block elements-i study of aluminium chloride study of aluminium structure of some compounds

Aluminium (III) chloride forms a dimer because aluminium :

  1. cannot form a trimer.

  2. has high ionization energy.

  3. belongs to third group.

  4. can have higher coordination number.
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

 Aluminium trichloride is a dimer, $Al _2Cl _6$.

This is because: 
$AlCl _3$ forms a dimer as there is unsaturation in coordination. Also it enables Al atoms to complete their octets.

Aluminium is more like a metalloid than a metal.The electronegativity of aluminium is higher than the electronegativity of sodium .