Predicting Spontaneity of 2CO(g)+O2(g)=2CO2(g)

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In summary, the conversation discusses the effect of temperature on the spontaneity of a reaction, specifically in relation to the equilibrium constant. It is determined that when the signs of both ΔH and ΔS are the same, the reaction will be spontaneous at either low or high temperatures. When ΔH is negative and ΔS is positive, the reaction will be spontaneous at all temperatures, whereas when ΔH is positive and ΔS is negative, the reaction will not be spontaneous. The total moles of reactants and products also play a role in determining the spontaneity of the reaction.
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reconrusty
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Homework Statement


Will the following processes be spontaneous only at high temperatures, only at only temperatures, at all temperatures, or at no temperatures?

2CO(g)+O2(g)=2CO2(g)
Delta(H)=-566kJ

Homework Equations

The Attempt at a Solution


So i just need to figure out how to predict the sign of Delta(S) but I am not sure how to do that with just the balanced equation given, any tips would be helpful.

Thanks!
 
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  • #2
I think this question is referring to the effect of temperature on the equilibrium constant. For an exothermic reaction (negative delta H), does the equilibrium constant increase with temperature or decrease with temperature?

Chet
 
  • #3
The total moles in the reactants are more than the products. This is decreasing entropy. If the total moles were more in the products, then this would be increasing entropy. So, when ΔH is negative, and ΔS<0 (decreasing entropy), we know that this is spontaneous at low temps.

The trends are as follows:
ΔS>0 and ΔH<0 Spontaneous (ΔG<0)
ΔS>0 and ΔH>0 spontaneous at high temps.
ΔS<0 and ΔH<0 spontaneous at low temps
ΔS<0 and ΔH>0 non-spontaneous (ΔG>0)

Notice that when the signs for both ΔS and ΔH are the same, it dictates the conditions of the reaction (H and S <0 are both spont. at low temps) and (H and S>0 are spont. at high temps). Hope this helps.
 

1. What is the equation for predicting spontaneity of 2CO(g)+O2(g)=2CO2(g)?

The equation for predicting spontaneity of 2CO(g)+O2(g)=2CO2(g) is ΔG° = ΔH° - TΔS°, where ΔG° is the change in free energy, ΔH° is the change in enthalpy, ΔS° is the change in entropy, and T is the temperature in Kelvin.

2. How do you determine the values for ΔH° and ΔS° in the equation?

The values for ΔH° and ΔS° can be determined using standard enthalpy and entropy values for the reactants and products. These values can be found in reference tables or calculated using experimental data.

3. What does a negative value for ΔG° indicate?

A negative value for ΔG° indicates that the reaction is spontaneous and will proceed in the forward direction. This means that the products have a lower free energy than the reactants, and the reaction will release energy.

4. Is the equation for predicting spontaneity of 2CO(g)+O2(g)=2CO2(g) applicable to all reactions?

No, the equation is only applicable to reactions that occur at constant temperature and pressure. It also assumes that the reaction is at equilibrium.

5. Can the equation predict the rate of a spontaneous reaction?

No, the equation only predicts the direction of a spontaneous reaction. The rate of a reaction is determined by factors such as concentration, temperature, and catalysts.

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