(a) Use the Born-Mayer equation for the lattice enthalpy and a BornHaber cycle to estimate the enthalpy of formation of CaCl(s). The sublimation enthalpy of Ca(s) is \(176 \mathrm{~kJ} \mathrm{~mol}^{-1}\) and it can be assumed that the ionic radius of \(\mathrm{Ca}^{+}\) is close to that of \(\mathrm{K}^{+}\); other necessary data are to be found in Example 15 C. 2 or in the tables in the Resource section.

(b) Show that an explanation for the nonexistence of CaCl(s) can be found in the reaction enthalpy for the disproportionation reaction \(2 \mathrm{CaCl}(\mathrm{s}) \rightarrow \mathrm{Ca}(\mathrm{s})+\mathrm{CaCl}_{2}(\mathrm{~s})\).

Text Transcription:

176 kJ mol^-1

Ca^+

K^+

2 CaCl(s) rightarrow Ca(s)+CaCl_2(s)

Chemistry Notes Unit Conversions – changing units -Consider what you know and what you want -cancel unwanted units e.g how many nickels are in $10 $10 = stand alone unit nickels $ 1 dollar = 20 nickels = relationship ($10/1) (20 nickels/$1) = 200 Always start with a stand alone unit Keywords for equal (=) Equal Related to In Has Contains For every We have to have units on opposite sides 1km ______=10 m 1km = 1000 m lbs kg g Know 55.0 kg bw = body weight per 55.0 kg bw 14.5 mg ibu = 1 kg bw 500. mg ibu = 1 mL Want mL (55.0 lbs /1) x ( 14.5 mg per weight/ 1kg) ( 1ml/500g per ibu) = 1.596 Note* multiply top/ divide by the bottom 1.596 = 1.60 mL How many grams are in 0.800 lbs 2.20 lbs = kg 1kg = 100 g (0.800lbs/1g)(1kg/2.2)(1kg/100g) Chemistry Notes Jan 25th2019, – An atom is mostly space protons are positive charge Neutron are neutral ( hence the name) Approximately 10 -5 Amu = atomic mass unit Culum = charge – opposites attract Interplay of protons ( p), neutrons (n), and electrons (e) that give the structure and propreties of the atoms -most matter is electrically neutral ( the same number of e’s and p’s) -element – identity = the number (#) of p = atomic number Isotopes – atom w/ same # of p , but diff # of n very in atomic mass, P + n