Tag: lattice energy

Questions Related to lattice energy

The magnitude of the lattice energy of a soild increases if:

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

  1. the ions are large

  2. the ions are small

  3. the ions are of equal size

  4. charges on the ions are small

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Correct Option: B
Explanation:

Lattice energy is directly proportional to the charge on the ions and inversely proportional to the size of the ions.  Smaller the size, greater is the lattice energy.

The higher lattice energy corresponds to 

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

  1. ${\rm{MgO}}$

  2. ${\rm{CaO}}$

  3. $4{\rm{SrO}}$

  4. ${\rm{BaO}}$

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Correct Option: B

Maximum lattice enthalpy is present in

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

  1. $K _{2}O$

  2. $CaO$

  3. $Al _{2}O _{3}$

  4. $KCl$

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Correct Option: D

The melting point of a material with low binding energy is:

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

  1. high

  2. low

  3. infinity

  4. negative

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Correct Option: B
Explanation:

The melting point of a material with low binding energy is low. When, the binding energy is low, the attraction between the valence electron and the nucleus is low. This also means that the intermolecular attraction is low. Hence, the melting point is low.

Which pair is not correct order of lattice energy?

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

  1. $KCI > MgO$

  2. $AlN > MgO$

  3. $BeCO _3 > MgCO _3$

  4. $KCI < MgO$

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Correct Option: A
Explanation:

Lattice Energy is directly proportional to the charge on the ions and inversely proportional the size of the ions. As size decreases, lattice energy increases. So $MgO$ have higher lattice energy than $KCl$.

The relation between the magnitudes of lattice energy of crystal and its formation energy is:

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

  1. lattice energy > formation energy

  2. lattice energy $=$ formation energy

  3. lattice energy < formation energy

  4. none of the above

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Correct Option: B
Explanation:

Lattice energy is the energy required to break apart an ionic solid and convert its component atoms into gaseous ions. The value of the lattice energy to always be positive.

Also, enthalpy of lattice formation is defined as the energy released when gaseous ions bind to form an ionic solid. The value is negative but has the same magnitude as lattice energy.
Hence, $B$ is correct.

If $Na^+$ ion is larger than $Mg^{2+}$ ion, and $S ^{2-}$ion is larger than $Cl^{-}$ ion, which of the following will be less soluble in water?

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

  1. $NaCl$

  2. $Na _{2}S$

  3. $MgCl _{2}$

  4. $MgS$

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Correct Option: D
Explanation:

The lattice energy of a salt  gives a rough indication of the solubility of the salt in water because it reflects the energy needed to separate the positive and negative ions in a salt. Sodium and potassium salts are soluble in water because they have relatively small lattice energies. Magnesium and aluminum salts are often much less soluble because it takes more energy to separate the positive and negative ions in these salts.

When sodium and chlorine react, energy is:

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

  1. released and ionic bond is formed.

  2. released and covalent bond is formed.

  3. absorbed and covalent bond is formed.

  4. absorbed and ionic bond is formed.

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Correct Option: A
Explanation:

When sodium and chlorine react, an ionic bond is formed, and formation of ionic bond is fast and exothermic.

Lattice energy of an ionic compound depends upon:

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

  1. charge on the ion and size of the ion

  2. packing of ions only

  3. size of the ion only

  4. charge on the ion only

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Correct Option: A
Explanation:

Lattice energy of ionic compound is directly proportional to charge on the ion and inversely propotional to size of ion.

Which of the following has higher lattice energy -$Al _2O _3$ or $Al _2Se _3$?

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

  1. $Al _2O _3$ > $Al _2Se _3$

  2. $Al _2O _3$ < $Al _2Se _3$

  3. $Al _2O _3$ = $Al _2Se _3$

  4. None of these

Show answer
Correct Option: A
Explanation:

Lattice Energy is directly proportional to the charge on the ions and inversely proportional to the size of the ions. The two species have the same charge but the size of $Se$ is greater than $O$. Hence lattoce energy of $Al _2O _3$ is greater than $Al _3Se _3$.