Tag: defining lattice energy

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Questions Related to defining lattice energy

Multiple choice chemistry lattice energy defining lattice energy ionic or electrovalent bond energy cycles

The lattice energies of the oxidies of $Mg,Ca,Sr \;$ and $\;Ba$ follow the order:

  1. $BaO\;>\;SrO\;>\;CaO\;>MgO$
  2. $CaO\;>\;BaO\;>\;SrO\;>\;MgO$
  3. $MgO\;>\;SrO\;>\;CaO\;>\;BaO$
  4. $MgO\;>\;CaO\;>\;SrO\;>\;BaO$
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

For oxides of the same group (alkaline earth metals), the lattice energy decreases as the size of the cation increases. Since the ionic radii follow Mg2+ < Ca2+ < Sr2+ < Ba2+, the lattice energy follows MgO > CaO > SrO > BaO.

Multiple choice chemistry lattice energy defining lattice energy ionic or electrovalent bond energy cycles

The order of increasing lattice energy of the following compounds is :

  1. $NaCl\;<\;CaO\;<\;NaBr\;<\;BaO$
  2. $NaBr\;<\;NaCl\;<\;BaO\;<\;CaO$
  3. $NaCl\;<\;NaBr\;<\;BaO\;<\;CaO$
  4. $NaBr\;<\;NaCl\;<\;CaO\;<\;BaO$
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Lattice energy depends on charge and size. CaO and BaO (2+, 2-) have much higher lattice energies than NaCl and NaBr (1+, 1-). Within the pairs, smaller ions (Ca2+ vs Ba2+; Cl- vs Br-) lead to higher lattice energy, so the order is NaBr < NaCl < BaO < CaO.

Multiple choice chemistry lattice energy defining lattice energy ionic or electrovalent bond energy cycles

From the following sequence calculate the lattice energy of AB(s):
$A(s)\rightarrow A(g)+e$;      $610\;kJ\;mol^{-1}$
$B(g)+e\rightarrow B(g);$      $-260\;kJ\;mol^{-1}$
$A(s)+B(g)\rightarrow AB(s);$      $-569\;kJ\;mol^{-1}$

  1. $-219$
  2. $-919$
  3. $+1539$
  4. $+301$
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation
The lattice energy of a crystalline solid is usually defined as the energy of formation of the crystal from infinitely-separated ions, molecules, or atoms. 
let the equations be 1, 2 and 3.
We will get the lattice energy by  $3-2-1 $= $-569+260-610$ $= -919$
Multiple choice chemistry lattice energy defining lattice energy ionic or electrovalent bond energy cycles

The lattice energies of $KF,KCl,KBr \;$ and $\;KI$ follows the order:

  1. $KF>KCl>KBr>KI$
  2. $KI>KBr>KCL>KF$
  3. $KF>KCl>KI>Br$
  4. $KI>KBr>KF>KCl$
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Lattice energy is directly proportional to the charge of the ions and inversely proportional to the size of the ions. Thus lattice energy increases as the size of anion decreases. 

Multiple choice chemistry lattice energy defining lattice energy ionic or electrovalent bond energy cycles

Identify the correct order of lattice energies.

  1. $CsCl < RbCl < KCl < NaCl$
  2. $KCl > CaCl _2 > AlCl _3$
  3. $NaCl < LiCl < MgCl _2 < AlCl _3$
  4. $LiCl > NaCl < MgCl _2 < AlCl _3$
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation
$I^{st}$ group elements lattice energy is inversly proportional to radius and directly proportional to charge.
According to question all compounds have same charge but radius differs.
The order of radius is $Cs>Rb>K>Na$ 
So order of lattice energy is $CsCl<RbCl<KCl<NaCl$

Multiple choice chemistry lattice energy defining lattice energy ionic or electrovalent bond energy cycles

The lattice energy of four ionic compounds $W, X, Y,$ and $Z$ are measured. The energies are found to be $-922\ kJ/mol, -769\ kJ/mol, -718\ kJ/ mol,$ and $-688\ kJ/mol$ respectively.
The four ionic, compounds are $NaCl, NaF, KBr$, and $KCl$.
Which of these ionic compounds could be identified as compound X based on the lattice energy?

  1. $NaCl$
  2. $NaF$
  3. $KBr$
  4. $KCl$
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Lattice energy magnitude increases with smaller ionic radii and higher charges. Among the compounds, NaF has the smallest ions and highest lattice energy, while KBr has the largest ions and lowest lattice energy. NaCl falls in the middle range.

Multiple choice chemistry lattice energy defining lattice energy ionic or electrovalent bond energy cycles

Boiling point of a substance is based on the intermolecular and intramolecular forces which in turn determine the lattice energy of a substance.
Which of the following substance would have the highest boiling point?

  1. $NaCl$
  2. $Hg$
  3. $AlF _{3}$
  4. $H _{2}O$
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

$NaCl$ will have the highest boiling point as it is the strongest ionic compound present in the given options. $NaCl$ have strong interionic forces as $Na^+$ and $Cl^-$ attracts each other very strongly which results in an increase in the compactness of the molecule, further its lattice enthalpy.

Multiple choice chemistry lattice energy defining lattice energy ionic or electrovalent bond energy cycles

We have all heard the phrase "opposites attract but like repels." This is especially true for ionic compounds.
Which one of the following has the largest lattice energy as a result of this attraction?

  1. $LiCl$
  2. $NaCl$
  3. $K _{2}O$
  4. $MgCl _{2}$
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

$LiCl$. $Li^+$ due to its small size and has high polarizing power and attracts the electron cloud of $Cl^-$ towards itself which results in high lattice energy of the molecule.

Multiple choice chemistry lattice energy defining lattice energy ionic or electrovalent bond energy cycles

Considering only  lattice enthalpy, arrange them in the increasing order of their stability:
$NaCl$ , $MgCl _{2}$ , $MgO$

  1. $NaCl$ , $MgO$, $MgCl _{2}$
  2. $NaCl$ , $MgCl _{2}$ , $MgO$
  3. $MgCl$, $MgO$, $MgCl _{2}$

  4. none of these
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Lattice enthalpy is a measure of the strength of the forces between the ions in an ionic solid. The greater the lattice enthalpy, the stronger the forces. 

Lattice enthalpy of $ NaCl $ = $787kJ/mol$
Lattice enthalpy of $ MgO $ = $3826kJ/mol$
Lattice enthalpy of $Mg{ Cl } _{ 2 }$= $+2534kJ/mol$