Tag: chemistry

Quizzes (490) Questions (9892)

Questions Related to chemistry

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

Select the correct order of lattice energy.

  1. $LiF\, <\, LiBr\, <\, LiI$
  2. $LiCl\, >\, LiBr\, >\, LiI$
  3. $LiCl\, >\, NaCl\, >\, KCl$
  4. $BeCO _3\, <\, MgCO _3\, <\, SrCO _3\, <\, BaCO _3$
Reveal answer Fill a bubble to check yourself
B,C Correct answer
Explanation

The lattice energy decreases in the order $LiCl\, >\, LiBr\, >\, LiI$. 

As the size of the anion increases from chloride to iodide, the lattice energy decreases.
The lattice energy decreases in the order $LiCl\, >\, NaCl\, >\, KCl$. 
As the size of the cation increases from lithium to potassium, the lattice energy decreases.

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

Lattice energy of ionic compounds depend upon:

  1. packing of ions only

  2. charge and size of ions

  3. charge on ion only

  4. size of ions only
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Lattice energy is defined as the heat of formation for ions of opposite charge in the gas phase to combine into an ionic solid. It is directly proportional to the charge on the ions and inversely proportional to the size of the ions. 

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

Which of the following compounds will have the largest lattice energy?

  1. $AlBr _3$
  2. $CaO$
  3. $LiBr$
  4. $MgBr _2$
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Among the cations, $Al^{3+},\ Ca^{2+},\ Li^{+}$ and $Mg^{2+}$, $Al^{3+}$ has the highest charge. Hence, $AlBr _3$ has the highest lattice energy. The lattice energy is directly proportional to the charge on the ion and inversely proportional to the size of the ion. 

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.