Chemical Equilibrium

RB # ______Name ______Row/Seat ______Date ______Per. _____

For items 1-8, underline the term inside the parentheses that makes each statement true.

1. At equilibrium, the rate of the forward reaction is (equal to, greater than) the rate of the reverse reaction.

2. The equilibrium constant for a given reaction at a given temperature is the (product, quotient) of the specific rate constant for the forward reaction and the specific rate constant for the reverse reaction.

3. The exponents used in the expression for the equilibrium constant are the (subscripts, coefficients) of the reactants and products.

4. If a reaction tends to go toward completion, the rate of the forward reaction is (greater than, less than, equal to) the rate of the reverse reaction before equilibrium is reached.

–5 5. If Keq = 1.2 x 10 , the concentration of the reactants is (greater than, less than) the concentration of the products at equilibrium.

6. At temperature T1, Keq for a certain reaction is 0.239. At temperature T2, Keq for the same reaction is 4.7. By changing the temperature from T1to T2, the equilibrium will shift in favor of the (reactants, products).

7. If the reaction H2(g) + Cl2(g)  2HCI(g) + heat is at equilibrium, a, decrease in (volume, temperature) will produce a shift in equilibrium toward the right.

8. An increase in pressure on the system 2CO2(g)  2CO(g) + 02(g) at equilibrium results in an equilibrium shift toward the (left, right).

Answer or complete each of the following items.

9. What factors can affect the equilibrium of a reaction? ______

______reaction 10. A reversible one-step reaction occurs between carbon monoxide gas, CO, and hydrogen gas, H2, to produce methane gas, CH4, and gaseous water. Using this information, fill in the diagram according to the following guidelines a. Within the ovals, write the balanced equation for the reaction. 5 b. Label “forward” and “reverse” reactions on the lines provided. (Write the words.) ______reaction c. In the rectangles, write the words reactants or products, as appropriate, to represent both the forward and reverse reactions.

Chemistry-2 Chemical Equilibrium Page 1 11. Write the expression for the equilibrium constant for the reaction in question 10.

12. In the reaction in question 10, if the volume of the reaction vessel and temperature are kept constant and the pressure on the system is increased,

a. the concentrations of which substances would be affected? ______(reactants or products) b. in which direction will the equilibrium shift? ______

c. which substance(s) will show an increase in concentration when equilibrium is reestablished?

______

13. Consider the equilibrium equation for the reaction: 4HCl(g) + 02(g) + heat  2C12(g) + 2H20(g)

a. If the temperature is increased, the reaction will favor the formation of ______(reactants or products) b. Which reaction requires an input of energy? ______(forward or reverse) 14. The Haber process is used for the industrial production of ammonia. It involves the reaction: N2(g) + 3H2  2NH3 + energy.

a. why is NH3 removed as it is formed? ______

______

b. why is the use of a catalyst considered one of the optimum conditions for this process?

______

c. what is the effect on the relative amounts of product and reactant if the catalyst is removed?

______

4 6 [NO] [H2O] 15. Given Keq = 4 5 [NH3] [O2]

a. Write the chemical equation for the reversible reaction having the given Keq.

______

b. At a certain temperature the concentrations of NO and NH3 are equal, and the concentration of H2O and O2 are 2.0 M and 3.0 M respectively. What is the value of Keq at this temperature?

Chemistry-2 Chemical Equilibrium Page 2

Equilibrium Vocabulary

chemical equilibrium ion product reversible reaction coefficient Keq saturated solution concentration Ksp shift dissociation equation Le Châtelier’s principle solubility product constant double arrow mass-action expression solubility product expression equilibrium constant precipitate stress Haber process rate

A chemical change in which the reactants can be 1. ______re-formed from the products is called a(n) ______(1) . When forward and reverse reactions occur at the same 2. ______(2) , a state of ______(3) exists. A(n) ______(4) is used in an equation to symbolize this state. 3. ______

4. ______According to the law of chemical equilibrium, the (5) (6) ______, symbolized by ______, is numerically equal 5. ______to the fraction formed by the _____(7) _ of the reactants and the products raised to a power equal to the ______(8) of 6. ______each in the balanced equation. This fraction is called the ______.(9) 7. ______

When conditions such as temperature are 8. ______changed, a chemical reaction is said to be placed under a(n) __(10)_____. Under such changing conditions, 9. ______equilibrium can undergo a(n) ______(11) in the direction that tends to counteract the imposed changes. This 10. ______

(12) generalization is known as ______, which has been 11. ______applied to the manufacture of ammonia by a method called the ______.(13) 12. ______

The concentration of an ionic solid in contact 13. ______with a(n) ______(14) of that solid is a constant. This constant can be combined with the solution equilibrium 14. ______constant to produce the ______,(15) whose symbol is ______.(16) Given a(n) ______(17) showing the formation of 15. ______ions from a solid, we may write an expression, called a(n) ______,(18) to show what concentrations of ions, 16. ______raised to appropriate powers and divided, produce the 17. ______constant. Such an expression is sometimes called a(n) (19) ______. 18. ______

19. ______

Chemistry-2 Chemical Equilibrium Page 3

Chemical Equilibrium

For items 1-8, underline the term inside the parentheses that makes each statement true.

1. At equilibrium, the rate of the forward reaction is (equal to, greater than) the rate of the reverse reaction.

3. The exponents used in the expression for the equilibrium constant are the (subscripts, coefficients) of the reactants and products.

4. If a reaction tends to go toward completion, the rate of the forward reaction is (greater than, less than, equal to) the rate of the reverse reaction before equilibrium is reached.

–5 5. If Keq = 1.2 x 10 , the concentration of the reactants is (greater than, less than) the concentration of the products at equilibrium.

7. If the reaction H2(g) + Cl2(g)  2HCI(g) + heat is at equilibrium, a, decrease in (volume, temperature) will produce a shift in equilibrium toward the right.

8. An increase in pressure on the system 2CO2(g)  2CO(g) + 02(g) at equilibrium results in an equilibrium shift toward the (left, right).

Answer or complete each of the following items.

9. What factors can affect the equilibrium of a reaction? ______temperature, pressure, concentration of reactants and/or products

______forward reaction 10. A reversible one-step reaction occurs between carbon monoxide gas, CO, and hydrogen gas, H2, to produce methane reactants products gas, CH4, and gaseous water. Using this information, fill in the diagram according to the following guidelines CO(g) + 3H2(g) CH + H O 4(g) 2 (g) a. Within the ovals, write the balanced equation for the reaction. 5 b. Label the forward and reverse reactions products reactants on the lines provided. ______reverse reaction c. In the rectangles, write the words reactants or products, as appropriate, to represent both the forward and reverse reactions. 11. Write the expression for the equilibrium constant for the reaction in question 10. Chemistry-2 [CH Chemical] [H O] Equilibrium Page 4 K = 4 2 eq 3 [CO] [H2]

12. In the reaction in question 10, if the volume of the reaction vessel and temperature are kept constant and the pressure on the system is increased,

a. the concentrations of which substances would be affected? ______all of them

b. in which direction will the equilibrium shift? ______toward the right

c. which substance(s) will show an increase in concentration when equilibrium is reestablished?

______CH4 and H2O

13. Consider the equilibrium equation for the reaction: 4HCl(g) + 02(g) + heat  2C12(g) + 2H20(g)

a. If the temperature is increased, the reaction will favor the formation of ______products (Cl2, H2O) b. Which reaction requires an input of energy? ____the______forward reaction

14. The Haber process is used for the industrial production of ammonia. It involves the reaction: N2(g) + 3H2  2NH3 + energy.

a. why is NH3 removed as it is formed? ______the removal of products shifts

______equilibrium toward the formation______of more product

b. why is the use of a catalyst considered one of the optimum conditions for this process?

______it lowers the activation energy which speeds up the reaction.

c. what is the effect on the relative amounts of product and reactant if the catalyst is removed?

______none

4 6 [NO] [H2O] 15. Given Keq = 4 5 [NH3] [O2]

a. Write the chemical equation for the reversible reaction having the given Keq.

______4 NH3 + 5 O2  4______NO + 6 H2O

b. At a certain temperature the concentrations of NO and NH3 are equal, and the concentration of H2O and O2 are 2.0 M and 3.0 M respectively. What is the value of Keq at this temperature? Since [NO] = [NH3], they cancel out and are not part of the equation.

6 6 [H2O] [2.O] 64 Keq = = = = 0.26 [O ]5 [3.0]5 243 2

Chemistry-2 Chemical Equilibrium Page 5 Equilibrium Vocabulary

A chemical change in which the reactants can be 1. ______reversible reaction re-formed from the products is called a(n) ______(1) . When forward and reverse reactions occur at the same 2. ______rate ______(2) , a state of ______(3) exists. A(n) ______(4) is used in an equation to symbolize this state. 3.chemical ______equilibrium

4. ______double arrow According to the law of chemical equilibrium, the (5) (6) ______, symbolized by ______, is numerically equal 5. equilibrium______constant to the fraction formed by the ______(7) of the reactants and the products raised to a power equal to the ______(8) of 6. ______Keq each in the balanced equation. This fraction is called the ______.(9) 7. ______concentration

When conditions such as temperature are 8. ______coefficient changed, a chemical reaction is said to be placed under a(n) ______.(10) Under such changing conditions, 9.mass ______-action expression equilibrium can undergo a(n) ______(11) in the direction that tends to counteract the imposed changes. This 10. ______stress______

(12) generalization is known as ______, which has been 11. ______shift applied to the manufacture of ammonia by a method called the ______.(13) 12. ______Le Châtelier’s principle The concentration of an ionic solid in contact with a(n) ______(14) of that solid is a constant. This 13. ______Haber process constant can be combined with the solution equilibrium 14. ______precipitate (15) constant to produce the ______, whose symbol is (16) ______. Given a(n) ______(17) showing the formation of 15. ______solubility product _ ions from a solid, we may write an expression, called constant a(n) ______,(18) to show what concentrations of ions, 16. ______Ksp raised to appropriate powers and divided, produce the constant. Such an expression is sometimes called a(n) 17. ______dissociation equation ______.(19) 18. solubility______product expression

19. ______ion product

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