Tag: energy cycles

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Questions Related to energy cycles

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

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

  1. the ions are large

  2. the ions are small

  3. the ions are of equal size

  4. charges on the ions are small
Reveal answer Fill a bubble to check yourself
B Correct answer
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.

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

Maximum lattice enthalpy is present in

  1. $K _{2}O$
  2. $CaO$
  3. $Al _{2}O _{3}$
  4. $KCl$
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Lattice enthalpy increases with higher ionic charges and smaller ionic radii according to Born-Landener type relationships. Al2O3 contains highly charged Al3+ and O2- ions compared to singly or doubly charged ions in the other choices, resulting in a much higher lattice enthalpy.

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

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

  1. high

  2. low

  3. infinity

  4. negative
Reveal answer Fill a bubble to check yourself
B Correct answer
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.

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

Which pair is not correct order of lattice energy?

  1. $KCI > MgO$
  2. $AlN > MgO$
  3. $BeCO _3 > MgCO _3$
  4. $KCI < MgO$
Reveal answer Fill a bubble to check yourself
A Correct answer
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 $KCl$.

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

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

  1. lattice energy > formation energy
  2. lattice energy $=$ formation energy

  3. lattice energy < formation energy

  4. none of the above
Reveal answer Fill a bubble to check yourself
B Correct answer
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.

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

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?

  1. $NaCl$
  2. $Na _{2}S$
  3. $MgCl _{2}$
  4. $MgS$
Reveal answer Fill a bubble to check yourself
D Correct answer
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.

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

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

  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
Reveal answer Fill a bubble to check yourself
A Correct answer
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 $Al _3Se _3$.