Tag: lattice energy

Quizzes (3) Questions (61)

Questions Related to lattice energy

Multiple choice chemistry lattice energy born-haber cycle born-haber cycles energy cycles

The standard formation reaction for aluminium oxide is $4Al(s) + 6O(g)\rightarrow 2Al _2O _3(s)$. This statement is false because:

  1. aluminium is not in its standard state

  2. the reaction should be written for one mole of Al
  3. The reaction is prevented by a thin film of $Al _2O _3$ formed on the surface of Al

  4. none of these
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation
$2Al+3O _2\rightarrow Al _2O _3$

The enthalpy of the above reaction is enthalpy of formation as one mole of $Al _2O _3$ is forming from elemental aluminum and oxygen gas. 
Multiple choice chemistry lattice energy born-haber cycle born-haber cycles energy cycles

Standard enthalpy of formation $(\Delta H _f)$ of which of the following is zero at $25^0C$ ?

  1. White phosphorous

  2. Red phosphorous
  3. Red lead $(Pb _3O _4)$
  4. $H^+(g)$
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

White phosphors is the elemental form of phosphorus for which enthalpy of formation is zero, while, $H^+$ and $Pb _3O _4$ are not elemental forms.

Multiple choice chemistry lattice energy born-haber cycle born-haber cycles energy cycles

The enthalpy of hydrogenation for $1-pentene$ is $+126\ kJ/mol$. The enthalpy of hydrogenation for $1, 3-pentadiene$ is $+230\ kJ/mol$. Hence estimate the resonance magnitude of (delocalization) energy of $1, 3-pentadiene$.

  1. $22\, kJ/mol$
  2. $104\, kJ/mol$
  3. $252\, kJ/mol$

  4. cannot be calculated from this information
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Enthalpy of hydrogenation per bond$=+126\ kJ/mol$


Enthalpy of hydrogenation for 2 bonds$=+252\ kJ/mol$


Resonance energy$=252-230=22\ kJ/mol$

Multiple choice chemistry lattice energy born-haber cycle born-haber cycles energy cycles

The heats of neutralization of $CH _3COOH.HCOOH, HCN$ and $HClO$ are 13.2, 13.4,2.9 and 3.6 kcal/eq respectively. Then, the degree of hydrolysis for the respective ions will be in the order :

  1. $CH _3COO^- < HCOO^- < CN^- < ClO^-$
  2. $HCOO^- < ClO^- < CN^- < CH _3COO^-$
  3. $CH _3COO^- < CN^- < ClO^- < HCOO^-$
  4. $HCOO^- < CH _3COO^- < ClO^- < CN^-$
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Strong acid have high heat of neutralization and are very much stable so required high energy for dissociation. Hence, weak acids are hydrolysed at faster rate than strong acids.

Multiple choice chemistry lattice energy born-haber cycle born-haber cycles energy cycles

The heat change for the reaction: $C(s) + S(s)\rightarrow CS _2(l)$, known as:

  1. heat of transition

  2. heat of fusion

  3. heat of vapourisation

  4. heat of formation
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation
$C(s)+2S(s)\rightarrow CS _2(l)$
The heat change of the reaction is enthalpy of formation as 1 mole of $CS _2$ is being formed from elemental state of carbon as well as Sulphur.
Multiple choice chemistry lattice energy defining lattice energy ionic or electrovalent bond energy cycles

The stability of an ionic compound is mostly due to:

  1. ionization energy

  2. electron affinity

  3. lattice energy

  4. electronegativity
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Lattice energy is a measure of energy released in ionic crystals when the ions are brought together from infinity. It measures the attraction between ions so that they are held in a position. Ionic compound stability is mostly due to lattice energy.

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

Decreasing order of lattice energy of $FeO, Fe _2O _3, NaCl$ is:

  1. $NaCl>FeO>Fe _2O _3$
  2. $Fe _2O _3>FeO>NaCl$
  3. $NaCl>FeO=Fe _2O _3$
  4. $Fe _2O _3>NaCl>FeO$
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Lattice energy is directly proportional to the product of ionic charges and inversely proportional to the inter-ionic distance. Fe2O3 has the highest charge (+3, -2), followed by FeO (+2, -2), and NaCl has the lowest charge (+1, -1).