Module 4 Lesson 2 Exercises Answer Key squared square root

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1 Module Lesson Eerises Answer Key 1. The volume is 1 L so onentrations an be done by inspetion. Just substitute values and solve for K [ CO][ HO] K CO H (0.8)(0.8) (0.55) (0.55) K [CH ][HS] K [H ] [CS ] K [H ] [CS ] [HS] [CH ] (0.56)(0.16) (0.0898) [HS] ( ) (0.56)( )(0.0898) ( ) 0.15 [ HS] 0.61 mol/ L Rearrange the equilibrium law and solve for H S. Don t forget H S is squared. You need to take the square root.. First, find the onentrations of all speies. moles C Litres 10.0 mol CP.00 mol/ L 5.00 L 5.0 mol CH 5.00 mol/ L 5.00 L 5.00 mol CPH 1.00 mol/ L 5.00 L Module Lesson Eerises Key page 1

2 . (on t) Write equilibrium law and substitute values. [PH ] 6 (1.00) 6 K [P ][H ] K (5.00)(.00) 1.00 K (5.00)(6.0) K ZnO and Zn are both solids, so they do not appear in the equilibrium law epression. As suh, we an disregard them in our alulations. First, find the onentrations of all speies. moles C Litres.00 mol C CO L 6.00 mol/l.00 mol C CO L 8.00 mol/l Write equilibrium law and substitute values. K K (6.00) [CO ] [CO] (8.00) K Write equilibrium law and rearrange to solve for [I ] [HI] K [H ][I ] [HI] [I ] [H ]K (0.50) [I ] (0. 10)( 6.0) [I ] 0.05 Module Lesson Eerises Key page

3 6. Write equilibrium law and rearrange to solve for [NH ] [NH ] K [H ] [N ] [NH ] K [H ] [N ] [NH ] K [H ] [N ] [NH ] (10.0)(0.600) (0.100) [NH ] 0.16 [NH ] 0.65 mol/l Use the onentration to alulate the number of moles. moles C L moles (0.65 mol/l) (.00 L) moles 0.90 moles NH 7. The volume is one Litre, so the onentrations an be determined by inspetion. Substitute onentrations and alulate. [ NH ] K H N (0.10) K (0.15) (0.5) (0.010) (0.0075)(0.5) K Aording to the reation stoihiometry, if.00 moles of Cl are produed the same amount of Br will be produed. Br Cl.00 moles To determine the onentration of BrCl, we write the equilibrium law and rearrange the epression to solve for [BrCl] Module Lesson Eerises Key page

4 8. (on t) [ Cl][ Br] K [ BrCl] [ Cl][ Br] [ BrCl ] BrCl K [ Cl ][ Br ] K (.00)(.00) BrCl 11.1 BrCl 1. BrCl 1.0 mol/l 9. No volume is given so assume a 1 L ontainer. Aording to the reation stoihiometry, the moles of hydrogen and iodine produed should be equal. Sine we do not know their equilibrium amounts, we an assign them a value of. Let H and I Write the equilibrium law and substitute values, then solve for. [H ][I ] K [HI] 0.00 (0.50) (0.00)(0.50) (0.00)(0.5) » H I moles Module Lesson Eerises Key page

5 10. Find all onentrations..00 mol [ H ] [ Cl ].00 mol/l L Only initial onentrations are given. Sine we do not know what the equilibrium onentrations are we must set up an ICE table. We assign the hange in hydrogen and iodine onentrations as. H (g) + Cl (g) HCl (g) I C E K [ HI] [ H][ I] ( ) (.00 ) ( ) (.00 ) (.00 ) (.00 ) H Cl mol/l [ HCl] ( ) 6.50 m.5 ol/l Write equilibrium law and substitute the equilibrium values. Determine equilibrium onentrations using the value of Module Lesson Eerises Key page 5

6 11. We an disregard A, sine it is solid and does not appear in the equilibrium law. We must first find the onentration of B: C.8 moles.00 L. mol/l B We are not given equilibrium onentrations, so we set up an ICE table to determine equilibrium onentrations. We use to represent the hanges in onentrations. A (s) + B (g) C (g) I C Sine the oeffiients for both B and C are the same, every mole of B used up, produes a mole of C E ---. [ C] Write equilibrium law K and substitute the [ B] equilibrium values ( ) (. ) (. ) 8.8 (. ) B mol/L moles B C V 0.5 mol/l.00 L i ( )( ) 0.50 moles B Determine equilibrium onentration of B using the value of. Find the number of moles of B by multiplying onentration times volume. Module Lesson Eerises Key page 6

7 1. Determine the onentrations of oygen and arbon dioide. The arbon an be disregarded as it is a solid moles C O 5.0 mol/l.00 L.00 moles C CO 1.00 mol/l.00 L We do not know the equilibrium onentrations, so we set up an ICE table. The value of K is greater than 1 so the amount of produt should eeed the amount of reatant. This means at equilibrium there will be less O and more CO. C(s) + O (g) CO (g) I C - + E CO K O ( 5.0 ) ( 5.0 ) CO mol/L ( )( ) moles CV 5.0 mol/l.00l moles 50.0 moles CO Write the equilibrium law and substitute equilibrium onentrations. Eliminate denominator by multiplying both sides by the denominator. Solve for, then for the equilibrium onentration of CO. Find moles of CO. Module Lesson Eerises Key page 7

8 1. We an disregard NH Cl sine it is a solid. Sine we do not know equilibrium onentrations, we set up and ICE table. NH Cl (s) NH (g) + HCl (g) I C --- E ( ) K NH HCl ( ) NH [ N H ] mol/l [ NH ] 1. We are given initial onentrations and an equilibrium onentration. We an use an ICE table to find the missing equilibrium onentrations. When finding the hange in onentration we need to use stoihiometry. The equilibrium onentration of NO is.0 mol/l, so it inreases from 0 to.0 mol/l. As a result the N and O must derease by a stoihiometri amount. N + O NO I N 1O C (.0) 1.0 (.0) NO NO E Now we an substitute the equilibrium values into the equilibrium law to alulate the value of K [NO] K [N ][O ] (.0) (0.8)(0.8) Module Lesson Eerises Key page 8

9 15. We are given the initial number of moles and the volume of the ontainer. We must first onvert these to onentrations. C C C CO 0 C0 5.0 mol.5 mol/l.0 L 10.0 mol 5.0 mol/l.0 L 1.0 mol 0.50 mol/l.0 L To find K we need equilibrium onentrations, but we only are given the equilibrium onentration of CO. To find the other equilibrium onentrations, we will set up an ICE table and use stoihiometry to find the hanges in the reatant onentrations. CO + O CO I CO 1O C (.0).0 ( ) CO CO E [CO ] K [CO] [O ] (.5) (0.5)(.0).15 Module Lesson Eerises Key page 9