Consider the following reaction and situations 1 through 10. In the spaces provided, clearly indicate the best response to each situation. A. increase C. no change E. shift right B. decrease D. shift left F. cannot be determined C(s) + H2O(g) ⇌ CO(g) + H2(g) H > 0 1. What will be the effect upon the equilibrium if the pressure on the system is increased? 2. What will be the effect upon the concentration of CO if the concentration of H2 is decreased? 3. What will be the effect upon the equilibrium if the concentration of H2 is decreased? 4. What will be the effect upon the concentration of H2O if the concentration of H2 is increased? 5. What will be the effect upon the equilibrium if H2 is removed and more C is added? 6. What will be the effect upon the concentration of H2 if the amount of C is increased? 7. What will be the effect upon the equilibrium if the temperature and the concentration of H2 increases? 8. What will be the effect upon the concentration of CO if the temperature is increased? 9. What will be the effect upon the equilibrium if the concentration of H2O is decreased and CO is increased? 10. What will be the effect upon the equilibrium if a catalyst is added?

1. C. no change

2. A. increase

3. E. shift to the right

4. A. increase

5. E. shift to the right

6. A. increase

7. F. cannot be determined

8. B increase

9. D. shift to the left

10 F. cannot be determined

Explanation:

According to Le Chaterlier principle, when a reaction is in equilibrium and one of the constraints that affect reactions is applied, the equilibrium will shift so as annul the effects of the constraints.

From the equation: C(s) + H2O(g) ⇌ CO(g) + H2(g),

H is greater than 0, meaning that the system is endothermic, that is energy is absorbed.

1. If the pressure of the system is increased, there would be no change to the system because there are equal number of moles of products and reactants.

2. If H2 concentration is decreased, the equilibrium will shift to the right and more products will be formed. Hence, the concentration of CO will increase.

3. If H2 concentration is decreased, the equilibrium will shift to the right to annul the effects of the decrease in the concentration of a product.

4. If the concentration of H2 is increased, the equilibrium will shift to the left to annul the effects of increased concentration of a product. Hence, more H2O would be formed.

5. If H2 (a product) is removed, and C (a reactant) is added, more of the products will be formed in order to annul the effects of the actions. Hence, equilibrium will shift to the right.

6. If the amount of C (a reactant) is increased, the equilibrium will shift to the right. Hence, more H2 will be formed.

7. The reaction is endothermic, hence an increase in temperature will ordinarily shift the equilibrium to the right. However, the addition of H2 (a product) is supposed to shift the equilibrium to the left. Hence, the effects of simultaneous addition of the two actions become indeterminate.

8. Since the reaction is endothermic, increase in the temperature of the system will shift the equilibrium to the right. Hence, more CO will be formed.

9. If the concentration of H2O (a reactant) is decreased and that of CO (a product) is increased, both actions lead to the equilibrium being shifted to the left.

10. Addition of catalyst to the system will only speed up the rate at which the system reach the equilibrium.

answer: the enthalpy of the overall chemical reaction is +87.88 kj or +88 kj.

according to hess's law, the overall enthalpy of a reaction is the difference between the sum of enthalpy values of all the products and the sum of enthalpy values of all the reactants.

δh(reaction) = ∑nδh(products) - ∑nδh(reactants)

δh(reaction) = [δh +δh] - [δh]

δh(reaction) = [1(-287.02) + 1(0) ] - [1(-374.9)] kj = +87.88 kj

here, δh (pcl3) = -287.02 kj, δh(cl2) = 0, δh(pcl5) = -374.9 kj

therefore, enthalpy of the overall reaction is +87.88 kj or +88 kj.