Compute the concentration (count per volume) of vacancies in copper at room temperature if the lattice parameter of FCC copper is 0.3615 nm at room temperature (25oC, 298 K), and the activation energy to form a single vacancy is 0.9 eV. Use 8.617x10-5 eV/(atom-K), exactly, as Boltzmann's Constant. Note: You could look up the density and atomic weight of copper to compute room temperature atom concentration you need for this problem.

explanation:

0.07 g/cm³

1.37 g/cm³

answer: - first one is the correct answer. .

explanations: - potassium sulfide is and cobalt(ii) chloride is .

charge on k is +1, charge on s is -2, charge on co is +2 and charge on cl is -1.

in a double replacement reaction the ion exchange takes place. in general the reaction looks like:

if one of the product is insoluble as per solubility rules then a precipitate of it is formed.

when we mix the aqueous solutions of potassium sulfide and cobalt(ii) chloride then chloride ion goes with potassium ion and sulfide ion goes with cobalt ion and the balanced equation is written as:

k and cl has equal charges, similarly co and s has equal charges and hence no subscripts are used for the product side.

as per the solubility rules, cos is insoluble and so it's precipitate is formed.

looking at the given choices, first choice is correct.