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Chemical Equilibrium RB # ______ Name _____________________________ Row/Seat ______ Date _____________________ Per. _____ 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. 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. 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? _________________________________________________________________________________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
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