To understand the difference between thermodynamic and kinetic properties of a chemical process. thermodynamics quantifies the state functions of a system. the state functions are independent of the path followed by the reaction, and depend only on the difference between the beginning and the final points of the reaction. the general thermodynamic formula that is used to predict the spontaneity of a chemical reaction is the gibbs free energy, defined as follows: δg∘=δh∘−tδs∘, whereδg∘ is the standard change in free energy from the reaction, δh∘ is the standard change of enthalpy (heat flow) in the reaction, t is the temperature in kelvins, and δs∘ is the standard change in entropy (disorder) during the reaction. if δg∘ is negative for a given reaction, it means that there will be a net flow of free energy from the reacting system into the environment, and the reaction is favored thermodynamically. such a reaction is said to be spontaneous. be aware, however, that spontaneous does not mean instantaneous, and that thermodynamically favored reactions may still occur very slowly. for example, the hydrogenation of ethene, h2c=ch2, to form ethane, h3c−ch3, is a thermodynamically favored reaction for which δg∘=−125 kj/mol. however, when hydrogen gas, h2, and ethene are mixed together at room temperature, they react spontaneously, but at a rate so slow as to be undetectable. from this example you can see that thermodynamics can predict whether a reaction is favored, but it says nothing about the rate at which the reaction will occur. to understand rates of reactions, we must turn to chemical kinetics. the reason that the above reaction occurs so slowly is that bonds must be broken before anything else can proceed. the bond-breaking event requires a certain amount of energy. this energy barrier is known as the activation energy of the reaction. adding platinum to this reaction will increase the reaction rate because the platinum acts as a catalyst. a catalyst speeds up a chemical reaction by lowering the activation energy but is not used up in the reaction. in this case, the platinum break the hydrogen-hydrogen bonds in h2, thus lowering the energy barrier. it is important to note that catalysts do not change the thermodynamic properties of a reaction. a catalyst cannot change the equilibrium constant of a reaction. some other common metal catalysts, in addition to platinum, are copper, iron, nickel, palladium, rhodium, and ruthenium. to increase the accessible surface area, they can sometimes be mixed with an inert substance such as charcoal.

1)

the reaction between carbon tetrachloride, ccl4, and water, h2o, to form carbon dioxide, co2, and hydrogen chloride, hcl, has a δg∘ value of −232 kj/mole, and so is thermodynamically favored. but when you mix carbon tetrachloride with water, no change is observed. what is a possible explanation for this?

the reaction between carbon tetrachloride, , and water, , to form carbon dioxide, , and hydrogen chloride, , has a value of , and so is thermodynamically favored. but when you mix carbon tetrachloride with water, no change is observed. what is a possible explanation for this?

the reaction is not favored thermodynamically.
it is a slow reaction kinetically.
the activation energy of the reaction is too small.
the reaction is not spontaneous.

2)

what word best describes the role that the palladium plays in the reaction between propene and hydrogen above?

what word best describes the role that the palladium plays in the reaction between propene and hydrogen above?

it is a catalyst.
it is an activation energy barrier.
it is a solvent.
it is a reagent.

3)

what did the palladium do to to increase the rate of the reaction between the propene and hydrogen?

what did the palladium do to to increase the rate of the reaction between the propene and hydrogen?

it changed the thermodynamic equilibrium.
it made the gibbs free energy of the reaction more positive.
it lowered the activation energy of the reaction.
it increased the activation energy of the reaction.