Question

The oxidation of copper(I) oxide, Cu2O(s) , to copper(II) oxide, CuO(s) , is an exothermic process.

2Cu2O(s)+O2(g)⟶4CuO(s)

The change in enthalpy upon reaction of 70.64 g Cu2O(s) is −72.08 kJ .

Calculate the work, 𝑤 , and energy change, Δ𝑈rxn , when 70.64 g Cu2O(s) is oxidized at a constant pressure of 1.00 bar and a constant temperature of 25∘ C .

Note that Δ𝐸rxn is sometimes used as the symbol for energy change instead of Δ𝑈rxn .

Answer 1

[AI-generated answer — Explain Bot]

To calculate the work, 𝑤, and energy change, Δ𝑈rxn, we need to use the information given and relevant equations.

First, let's calculate the number of moles of Cu2O(s) used in the reaction:

Molar mass of Cu2O = 2 * Atomic mass of Cu + Atomic mass of O = (2 * 63.55 g/mol) + 16.00 g/mol = 143.10 g/mol

Number of moles of Cu2O = Mass of Cu2O / Molar mass of Cu2O
= 70.64 g / 143.10 g/mol
≈ 0.493 mol

Now, let's calculate the work using the equation:
𝑤 = −PΔ𝑉

Since the pressure, P, is given as 1.00 bar and the reaction is taking place at constant pressure, we need to determine the change in volume, Δ𝑉.

To find Δ𝑉, we use the ideal gas law equation:
PV = nRT

Since the pressure, P, and temperature, T, are given, we need to determine the initial and final volumes, V.

The initial volume, V_initial, can be obtained from the number of moles and molar volume of Cu2O:
V_initial = n_initial * V_molar

The final volume, V_final, can be obtained from the number of moles and molar volume of CuO after the reaction:
V_final = n_final * V_molar

Given that the molar volume at STP (standard temperature and pressure) is 22.4 L/mol, we have:
V_initial = 0.493 mol * 22.4 L/mol
V_final = 4 * 0.493 mol * 22.4 L/mol

Now we can calculate Δ𝑉:
Δ𝑉 = V_final - V_initial

Finally, we can calculate the work:
𝑤 = −P * Δ𝑉

Next, let's calculate the energy change, Δ𝑈rxn, using the equation:
Δ𝑈rxn = Δ𝐻rxn - 𝑤

Given that Δ𝐻rxn is -72.08 kJ, we can substitute the values to find the energy change.

Remember to convert the temperature to Kelvin (25°C + 273.15 = 298.15 K) in order to use the ideal gas law equation.

By following these steps and performing the necessary calculations, you should be able to find the values of work, 𝑤, and energy change, Δ𝑈rxn.