contestada

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 42.60 g Cu2O(s) is −43.47 kJ . Calculate the work, ???? , and energy change, Δ????rxn , when 42.60 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 Δ????rxn .

Respuesta :

okpalawalter8

Answer:

The work is  

      [tex]W = -0.369kJ[/tex]

The energy  change of the reaction is  [tex]\Delta U _{rxn} = 43.839 kJ[/tex]  

Explanation:

From the question we are told that

    The chemical equation for this reaction is

             [tex]2 Cu_2 O + O_2_{(g)} ----> 4 CuO_{(s)}[/tex]

     The mass of  [tex]Cu_2 O[/tex] is  [tex]m = 42.60g[/tex]

      The enthalpy [tex]Cu_2 O[/tex] is  [tex]\Delta H_{re} = -43.47 \ kJ[/tex] this also the change in energy in terms of heat

      The pressure at which it is oxidized is [tex]P = 1\ bar[/tex]

The  no of moles of [tex]Cu_2 O[/tex]used in this reaction is mathematically represented as

        [tex]n = \frac{mass \ of \ Cu_2 O}{Molar \ mass \ of \ Cu_2 O}[/tex]

The molar mass of [tex]Cu_2 O[/tex] is  a constant with a value  [tex]M = 143.1 g/mol[/tex]

   Now substituting values

             [tex]n = \frac{ 42.60}{143.1}[/tex]

            [tex]n = 0.29769 \ moles[/tex]

From the reaction we see that

Two mole of [tex]Cu_2 O[/tex]  reacts with One mole of [tex]O_2[/tex] to give Four moles of  [tex]CuO_{(s)}[/tex]

This means that

One mole of  [tex]Cu_2 O[/tex]  reacts with 0.5 mole of [tex]O_2[/tex] to give two moles of  [tex]CuO_{(s)}[/tex]

it also implies that

[tex]0.29769 \ mole[/tex] of  [tex]Cu_2 O[/tex]  reacts with [tex]0.5 * 0.29769[/tex] moles of [tex]O_2[/tex] to give [tex]2* 0.29769[/tex] moles of  [tex]CuO_{(s)}[/tex]

so

[tex]0.29769 \ mole[/tex] of  [tex]Cu_2 O[/tex]  reacts with [tex]0.149[/tex] moles of [tex]O_2[/tex] to give [tex]0.595[/tex] moles of  [tex]CuO_{(s)}[/tex]

Now the number of moles of gaseous reactant is

      [tex]N_{O_2} = 0.149 \ moles[/tex]

The number of moles of gaseous product  is

     [tex]N_p = 0 \ moles[/tex]

So the change in number of moles for gaseous  compounds is mathematically evaluated as

         [tex]\Delta N = 0- 0.149 \ moles[/tex]

        [tex]\Delta N = - 0.149 \ moles[/tex]

Now the workdone for  the compound [tex]Cu_2 O[/tex] is mathematically represented as

        [tex]W = \Delta N RT[/tex]

Where R is the gas constant with a value of [tex]R = 8.314 J/mol \cdot K[/tex]

            T is the temperature with a value  [tex]T = 25 + 273 = 298 K[/tex]

     Substituting values

     [tex]W = -0.149 * 8.314 * (298)[/tex]

     [tex]W = -0.369kJ[/tex]

Generally the internal energy change of the reaction can be represented as

           [tex]\Delta U _{rxn} = \Delta H_{re} - W[/tex]

Substituting value

        [tex]\Delta U _{rxn} = -43.47 - (-0.369)[/tex]

        [tex]\Delta U _{rxn} = 43.839 kJ[/tex]  

This is the internal energy change on the reaction for 42.60 g of [tex]Cu_2 O[/tex]

       

Otras preguntas

Q&A Education