Answer to Question #217011 in General Chemistry for You

Question

For the reaction 2 Cu₂O (s) + O₂ (g)  →

→ 4 CuO (s), calculate ΔG^o (in kJ) at 500 K.

Answer 1

The moles of the Cu2O

Moles = mass / molar mass

Moles of Cu2O = 91.36 g / 143.091 g per mol = 0.63847 mol Cu2O

Now lets calculate the moles of the O2

1 mol O2 = 2 mol Cu2O

0.63847 mol Cu2O* 1 mol O2 / 2 mol Cu2O = 0.31923 mol O2

Now lets calculate the volume of the O2 using the ideal gas equation

PV= nRT

Where n = moles , P=pressure , T= Kelvin temperature , V= volume in L and R= gas constant (0.08206 L atm per K. mol )

V= nRT/P

V= 0.31923 mol * 0.08206 L atm per K. mol * 298 K / 0.9869 atm

V= 7.91 L atm

Now lets convert L atm to Joules

7.91 LK atm * 101.325 J / 1 L atm = 801 J

Convert Joules to kJ

801 J * 1 kJ / 1000 J = 0.801 kJ

Therefore the amount of work done = 0.801 kJ

Now lets calculate the change in the energy of the system

Delta U= q+W

q= -93.22 kJ

delta U = -93.22 kJ + 0.801 kJ

Delta U = -92.42 kJ

Therefore change in the energy = - 92.42 kJ