A decorative "ice" sculpture is carved from dry ice (solid CO2) and held at its sublimation point of –78.5°C. Consider the process in which a CO2 sculpture, weighing 389 g, sublimes on a granite tabletop. The temperature of the granite is 12.0°C and the process occurs reversibly. Assume a final temperature for the CO2 vapor of –78.5°C. The enthalpy of sublimation of CO2 is 26.1 kJ/mol. a. Calculate the entropy of sublimation for carbon dioxide (the system) ___ J/Kmol b. Calculate the entropy of the universe for this reversible process. Use three significant figures in the answer __J/K

Given:

Now,

The Entropy of sublimation of CO₂ will be:

=

By substituting the values, we get

=

=

Thus the answer above is right.

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The answers to the questions are;

a. The entropy of sublimation for carbon dioxide (the system) is  

134.07 J/Kmol.

b. The entropy of the universe for this reversible process is 376 J/K.

Explanation:

Entropy of sublimation is the entropy change experienced following the transformation of a mole of solid to vapor at  the temperature where the sublimation is taking place

a. We note that the mass of the solid CO₂ = 389 g

Molar mass of CO₂ = 44.01 g/mol

Number of moles of CO₂ in the sculpture = Mass/(Molar mass)

= (389 g)/(44.01 g/mol) = 8.84 Moles

Entropy of sublimation is given by

ΔS = - S =

Where:

ΔH  = 26.1 KJ/mol

T = Temperature = –78.5°C = ‪194.65‬ K

Therefore the amount of heat required to cause the 389 g of dry ice to sublime =    26.1 KJ/mol  × 8.84 Moles = 230.695 KJ

Therefore the entropy of sublimation = ΔS =

= 1.185 KJ/K

= 1185 J/K = 1185/8.84 J/Kmol = 134.07 J/Kmol

b. The entropy of the universe is given by;

ΔS = + ΔS  

If the heat absorbed by the system is the same as the heat given off by the surrounding, then we have;

ΔS =    

                =1.185 KJ/K - = 1.185 KJ/K - 0.809 KJ/K = 0.376 KJ/K

= 376 J/K.

b..

is the correct one

explanation:

covalent bonds form as valence electrons are shared between two atoms. lewis structures and structural formulas are common ways of showing the covalent bonding in organic molecules. formal charge describes the changes in the number of valence electrons as an atom becomes bonded into a molecule.

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explanation: