Biology Forums - Study Force

1. Define activation energy




2. State and explain the result on the reaction rate if each of the following factors is decreased.

Temperature:


Concentration:



Surface Area:



Use the following information to answer question 3
Ethanol is the alcohol found in beer, wine, and whiskey. In the production of ethanol, the starch in barley, grapes, or corn is reacted to form glucose in the presence of enzymes. During the fermentation process, yeast is added to the glucose. The yeast contains enzymes that act as biological catalysts in the reaction of glucose into ethanol and carbon dioxide. The reaction may be represented by the equation

C6H12O6(s) → 2 CO2(g) + 2 C2H5OH(l)


3a. The molar enthalpy of reaction for the fermentation of glucose is  _____ kJ/mol.
(show all work)












3b: Draw and energy pathway diagram for the uncatalyzed chemical reaction (assume this
      zcbmadgjl Schroderus


is a one-step reaction)
Ensure that your graph:
Includes a title
Has labelled axis
Includes reactants and products
Enthalpy Change
Activation Energy










3c:  On the same graph draw the catalyzed pathway
Draw the reaction pathway that would result if yeast was added
Label the location of the activated complex on your graph

3d: The enthalpy change for the catalyzed reaction is: __________ kJ/mol


Use the graph below to answer question 4.
      zcbmadgjl Schroderus



Y
X
ii
i
Ep (kJ)
Reaction Coordinate




4a) Is the reaction shown above endothermic or exothermic?

4b) What do ‘i' and ‘ii’ represent on the graph?


4c) Explain the energy changes that occur at different points during the reaction progress, referring to the conditions needed for a successful reaction, activated complex, as well as potential and kinetic energy.












      zcbmadgjl Schroderus


Use the information below to answer question 5

Oil refining plants use an exothermic process called cracking to transform ethyne, , into ethene and ethane with the use of a palladium catalyst.  This is represented by the reaction shown below:



5a) Draw and energy pathway diagram for the uncatalyzed chemical reaction (assume this is a one-step reaction)

Ensure that your graph:
Includes a title
Has labelled axis
Includes reactants and products
Enthalpy Change
Activation Energy








      zcbmadgjl Schroderus

5b: State and explain the effect of the palladium catalysts on

Activation Energy:



Yield of Product:



Enthalpy Change:



5c) Draw and energy pathway diagram for the reverse uncatalyzed chemical reaction (assume this is a one-step reaction)

Ensure that your graph:
Includes a title
Has labelled axis
Includes reactants and products
Enthalpy Change
Activation Energy


      zcbmadgjl Schroderus




5d) Compare the forward and reverse reaction in relation to:

Activation Energy



Magnitude of the Enthalpy Change:

#1

Activation energy is the minimum total kinetic energy that molecules must bring to their collisions for a chemical reaction to occur

#2

a) If we decrease the temperature, the reaction rate also decreases. When the temperature lowers, the molecules move slowly and exhibit less kinetic energy. So they collide less. So the rate of reaction also decreases.

When we increase the temperature, the kinetic energy of the molecule increases, and the collision of the particle also increases. As a result, the rate of reaction also increases.

b)

If the concentration of the reactant decreases, it led to a decrease in the collision of that reactant in the specific time period. So the rate of reaction also decreases.

c) Surface area also affects the reaction rate. If the surface area of the particles decreases, the frequency of the collision decreases. As a result the reaction rate also decreases.

If the surface area of the reactant is increased, the particles collide quickly and so the reaction rate also increases.

#3 (b)

Thank you.

TY :)