Question

Mercury(I) chloride consists of dimeric mercury(I) cations (with a formula of Hg₂²⁺) ionicly bonded to chloride ions forming an ionic lattice of Hg₂Cl₂(s). Elemental mercury reacts with chlorine dioxide gas to produce mercury(I) chloride and oxygen gas.

(a) Write the balanced chemical equation for this reaction.

(b) Calculate Delta H_rxn for this process.

(c) Is chlorine dioxide gas likely to be diamagnetic or paramagnetic? Explain how you know.

(d) Is the magnitude of the lattice energy of Hg₂Cl₂ more likely to be closest to the lattice energy of CsCl, BaCl₂, or BaO? Explain your choice.

Answer 1

formator (a) aHg + 2.0102 - Higl, + 402 O OHqxN - AH, (products ) oH (reactants) = [DH for Hqzcle + oH for Oz] - [DH for (02] x2 [-265 kJ/mol +0]- [104.6 kr/mofx2]

Delta H formation of Hg is not taken as we are taking elemental Hg , Delta H formation of 2 molecules of ClO2 is taken which is 2× 104.6 KJ/ mol, Delta H formation of 1 molecule of Hg2Cl2 is (-265KJ/mol), delta H formation of 4 molecules of O2 is zero .

delta H for our reaction = (-474 KJ/mol).

(C) ClO2 gas is paramagnetic as the central Chlorine atom has unpaired electrons.

: öö: e, ate to the unpaired elieton

Paramagnetism is exhibited by those that have unpaired electrons present in it.

(D) Lattice energy is the energy required to break the crystal alttice into its consitityent gaseous ions and it is directly proportional to the charge of ions and inversely proportional to the size of ions. That means lattice formed from ions of small sizes and high charges are highly stable.

Lattice energy of CsCl is -633KJ/mol

Lattice energy of BaCl2 is approximately -2053 KJ/mol

Lattice energy of BaO is approximately -3054KJ/mol.

The difference between lattice energy and lattice enthalpy is that :-

Lattice energy is a negetive valuewhereas lattice enthalpy is a positive value .

As lattice energy depends on size we can see from above ecamples that Cs⁺ ion which is more larger than Ba²⁺ ion has lower lattice energy than barium ion .

So the lattice energy of Hg₂Cl₂  will be more closest to BaCl2 beacuse they both have 2 Cl^- ions in their crystal and they both have a total of +2 charge in their lattice. Cs ion is very much larger than Ba. So BaCl2 is more comparable with Hg2Cl2.