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barxatty [35]
3 years ago
7

For a given reaction, ΔH=78.7kJ/mol, and the reaction is spontaneous at temperatures above the crossover temperature, 461K. The

value of ΔS= _______ J/mol⋅K, assuming that ΔH and ΔS do not vary with temperature.
Chemistry
1 answer:
TiliK225 [7]3 years ago
7 0

Answer:

171 J/mol.K

Explanation:

The spontaneity of a reaction depends on the Gibbs free energy (ΔG). If ΔG < 0, the reaction is spontaneous. The Gibbs free energy is related to the enthalpy (ΔH) and the entropy (ΔS) of the reaction through the following expression:

ΔG = ΔH - T.ΔS

where,

T is the absolute temperature

If ΔG < 0,

ΔH - T.ΔS < 0

ΔH < T.ΔS

ΔS > ΔH/T = (78.7 × 10³ J/mol)/461 K = 171 J/mol.K

ΔS must be at least 171 J/mol.K for the reaction to be spontaneous above 461 K.

You might be interested in
A chemist has 3.55x1022 molecules of nitrogen monoxide. How
Alina [70]

Answer:

<h2>0.059 moles</h2>

Explanation:

To find the number of moles in a substance given it's number of entities we use the formula

n =  \frac{N}{L} \\

where n is the number of moles

N is the number of entities

L is the Avogadro's constant which is

6.02 × 10²³ entities

From the question we have

n =  \frac{3.55 \times  {10}^{22} }{6.02 \times  {10}^{23} }  \\  = 0.05897...

We have the final answer as

<h3>0.059 moles</h3>

Hope this helps you

6 0
3 years ago
What is the mass of the light bulb and paperclips together? a. 250.1 g b. 246.0 g c. 251.0 g d. 205.10 g
ololo11 [35]

251.0 is the correct mass  of the light bulb and paperclips together.

<h3>What is mass ? </h3>

Mass is a physical body's total amount of matter. Inertia, or the body's resistance to acceleration when a net force is applied, is also measured by this term. The strength of an object's gravitational pull to other bodies is also influenced by its mass. The kilogram serves as the SI's fundamental mass unit.

For a body, mass is constant. Mass can be calculated using the formula: mass = volume density. A mass's weight is a measurement of the gravitational force at work on it. The kilogram is the SI unit of mass.

The mass of the substance will therefore be calculated as follows: MASS OF A SUBSTANCE = VOLUME DENSITY.

So finally we can say that the mass of the light bulb and paperclips together is 250.1g.

To know more about Mass please click here : brainly.com/question/19385703

#SPJ4

4 0
2 years ago
What is the total number of molecules in 11.2 liters of N2 gas at STP
scoray [572]
Molar volume at STP = 22,4 L

1 mole -------------- 22,4 L
 x mole -------------- 11,2 L

x = 11,2 / 22,4

x =  0,5 moles of N2

1 mole --------------- 6,02.10²³ molecules
0,5 moles ------------ y molecules

y = 0,5 . 6,02.10²³

y = 3,01.10²³ molecules 

7 0
3 years ago
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 c
dem82 [27]

Answer:

The work is  

      W = -0.369kJ

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

Explanation:

From the question we are told that

    The chemical equation for this reaction is

             2 Cu_2 O + O_2_{(g)} ----> 4 CuO_{(s)}

     The mass of  Cu_2 O is  m = 42.60g

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

      The pressure at which it is oxidized is P = 1\  bar

The  no of moles of Cu_2 Oused in this reaction is mathematically represented as

        n = \frac{mass \ of   \ Cu_2 O}{Molar \ mass \  of   \ Cu_2 O}

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

   Now substituting values

             n = \frac{ 42.60}{143.1}

            n = 0.29769 \ moles

From the reaction we see that

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

This means that

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

it also implies that

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

so

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

Now the number of moles of gaseous reactant is

      N_{O_2} = 0.149 \ moles

The number of moles of gaseous product  is

     N_p = 0 \ moles

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

         \Delta N = 0- 0.149 \ moles

        \Delta N = - 0.149 \ moles

Now the workdone for  the compound Cu_2 O is mathematically represented as

        W = \Delta N RT

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

            T is the temperature with a value  T = 25 + 273 = 298 K

     Substituting values

     W = -0.149 * 8.314 * (298)

     W = -0.369kJ

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

           \Delta U _{rxn} = \Delta H_{re} - W

Substituting value

        \Delta U _{rxn} = -43.47 -  (-0.369)

        \Delta U _{rxn} = 43.839 kJ  

This is the internal energy change on the reaction for 42.60 g of Cu_2 O

       

3 0
3 years ago
Record the volume of solution that will be delivered from the pipet pictures below in units of mL
zloy xaker [14]

Answer:

2a. 3mL.

2b. 10mL.

3. 38°C.

Explanation:

2a. We read the volume under the meniscus i.e under the curve.

The volume of the solution is 3mL.

2b. The volume of the pipette 10mL and the solution is at the calibration mark. Therefore, the volume of the solution is 10mL.

3. From the diagram given, we can see that 1 line represents 1 unit.

Now a careful look at the picture shows that the temperature is 38°C.

7 0
3 years ago
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