[HIO 4 ] (mol/l) [IO 4 ] (mol/l) [H 3 O + ] (mol/l) I C x +x +x E x x x

Transcription

1 54. Determine the ph of mol/l periodic cid solution, HIO 4 (q). The vlue for the rection below is HIO 4 (q) + H O(l) IO 4 (q) + H 3 O + (q) Wht Is Required? You must determine the ph of the solution of periodic cid. Wht Is Given? For HIO 4 (q), you know the initil concentrtion is mol/l. You know tht HIO 4 (q) hs of You hve blnced eqution for the cid-dissocition. Pln Your Strtegy Let represent the chnge in concentrtion in mol/l of HIO 4 (q) tht ionizes to rech equilibrium conditions. Using the stoichiometric reltionships in the blnced eqution nd the initil HCNO(q) concentrtion, set up n ICE tble for the equilibrium. Act on Your Strtegy See the ICE tble below. HIO 4 (q) + H O(l) IO 4 (q) + H 3 O + (q) [HIO 4 (mol/l) [IO 4 (mol/l) [H 3 O + (mol/l) I C + + E Write the epression for the rection. Substitute the equilibrium concentrtions nd the vlue of into the epression for. Re-rrnge the epression into qudrtic eqution. [H3O [IO 4 [HIO 4 [H3O [IO 4 [HIO 4 ( )( ) ( )( ) (0.084 ) = = = MHR Chemistry 1 Solutions Mnul

2 Use the qudrtic formul to solve for. b b 4c Clculte the ph using the eqution ph = log [H 3 O +. b b 4c (1) = or = (.9 10 ) (4)(1)( ) Becuse it is impossible to hve negtive concentrtion, cnnot equl Therefore, [H 3 O + = mol/l. ph = log [H 3 O + = log ( ) = 1.47 Check Your Solution The number of digits to the right of the deciml in the ph is the sme s the number of significnt digits in the initil concentrtion. The nswer seems resonble for wek cid hving this. Unit 4 Prt B MHR 185

3 55. Butylmine is monoprotic orgnic cid used in the mnufcturing of pesticides. It hs vlue of A chemist prepres solution of the cid with concentrtion of mol/l. Determine the ph of the solution. Wht Is Required? You must determine the ph of the solution of butylmine. Wht Is Given? For butylmine, you know the initil concentrtion is mol/l. You know tht butylmine hs of Pln Your Strtegy Write blnced eqution for the ciddissocition using the symbol HBu for butylmine. Let represent the chnge in concentrtion in mol/l of butylmine tht ionizes to rech equilibrium conditions. Using the stoichiometric reltionships in the blnced eqution nd the initil HBu(q) concentrtion, set up n ICE tble for the equilibrium. Act on Your Strtegy See the ICE tble below. HBu(q) + H O(l) Bu (q) + H 3 O + (q) [HBu (mol/l) [Bu (mol/l) [H 3 O + (mol/l) I C + + E Write the epression for the rection. Substitute the equilibrium concentrtions nd the vlue of into the epression for. Re-rrnge the epression into qudrtic eqution. [H3O [Bu [HBu [H3O [Bu [HBu ( )( ) ( )( ) (0.064 ) = = = MHR Chemistry 1 Solutions Mnul

4 Use the qudrtic formul to solve for. b b 4c Clculte the ph using the eqution ph = log [H 3 O +. b b 4c (1) = or = ( ) (4)(1)( ) Becuse it is impossible to hve negtive concentrtion, cnnot equl Therefore, [H 3 O + = mol/l. ph = log [H 3 O + = log ( ) = 5.90 Check Your Solution The number of digits to the right of the deciml in the ph is the sme s the number of significnt digits in the initil concentrtion. The nswer seems resonble for wek cid hving this. Unit 4 Prt B MHR 187

5 56. Triclopyr is wek monoprotic orgnic cid used to control brodlef weeds while leving grsses unffected. It hs vlue of A solution of this cid is prepred with n cid concentrtion of 0.07 mol/l. Wht is the ph of this solution? Wht Is Required? You must determine the ph of the solution of triclopyr. Wht Is Given? For triclopyr, you know the initil concentrtion is 0.07 mol/l. You know the triclopyr hs of Pln Your Strtegy Write blnced eqution for the ciddissocition using the symbol HTr for triclopyr. Let represent the chnge in concentrtion in mol/l of triclopyr tht ionizes to rech equilibrium conditions. Using the stoichiometric reltionships in the blnced eqution nd the initil HTr(q) concentrtion, set up n ICE tble for the equilibrium. Act on Your Strtegy See the ICE tble below. HTr(q) + H O(l) Tr (q) + H 3 O + (q) [HTr (mol/l) [Tr (mol/l) [H 3 O + (mol/l) I C + + E 0.07 Write the epression for the rection. Substitute the equilibrium concentrtions nd the vlue of into the epression for. Re-rrnge the epression into qudrtic eqution. [H3O [Tr [HTr [H3O [Tr [HTr ( )( ) ( )( ) (0.07 ) = = = MHR Chemistry 1 Solutions Mnul

6 Use the qudrtic formul to solve for. b b 4c Clculte the ph using the eqution ph = log [H 3 O +. b b 4c ( ) (4)(1)( ) (1) = or = Becuse it is impossible to hve negtive concentrtion, cnnot equl Therefore, [H 3 O + = mol/l. ph = log [H 3 O + = log ( ) = 1.95 Check Your Solution The number of digits to the right of the deciml in the ph is the sme s the number of significnt digits in the initil concentrtion. The nswer seems resonble for wek cid hving this. Unit 4 Prt B MHR 189

7 57. Nitrobenzene is monoprotic orgnic cid tht hs mny uses, one of which is in the mnufcturing of shoe nd floor polishes. = The ioniztion of the cid is given by the following rection: C 6 H 5 NO (q) + H O(l) C 6 H 4 NO (q) + H 3 O+(q) Determine the ph of 0.10 mol/l solution of the cid. Wht Is Required? You must determine the ph of the solution of nitrobenzene. Wht Is Given? You know the initil concentrtion of nitrobenzene is 0.10 mol/l. You know tht nitrobenzene hs of You hve the blnced eqution for the cid-dissocition. Pln Your Strtegy Let represent the chnge in concentrtion in mol/l of nitrobenzene tht ionizes to rech equilibrium conditions. Using the stoichiometric reltionships in the blnced eqution nd the initil concentrtion of nitrobenzene set up n ICE tble for the equilibrium. Act on Your Strtegy See the ICE tble below. C 6 H 5 NO (q) + H O(l) C 6 H 4 NO (q) + H 3 O+(q) [C 6 H 5 NO (mol/l) [C 6 H 4 NO (mol/l) [H 3 O + (mol/l) I C + + E 0.10 Write the epression for the rection. Substitute the equilibrium concentrtions nd the vlue of into the epression for. [H3O [C6H4NO [C H NO [H3O [C6H4NO [C6H5NO ( )( ) MHR Chemistry 1 Solutions Mnul

8 Re-rrnge the epression into qudrtic eqution. Use the qudrtic formul to solve for. b b 4c Clculte the ph using the eqution ph = log [H 3 O +. 4 ( )( ) (0.10 ) = = = 0 b b 4c (1) = or = ( ) (4)(1)( ) Becuse it is impossible to hve negtive concentrtion, cnnot Therefore, [H 3 O + = mol/l. ph = log [H 3 O + = log ( ) =.50 Check Your Solution The number of digits to the right of the deciml in the ph is the sme s the number of significnt digits in the initil concentrtion. The nswer seems resonble for wek cid hving this. Unit 4 Prt B MHR 191

9 58. Which solution is more cidic: mol/l solution of wek monoprotic cid with = or mol/l solution of wek monoprotic cid with = ? Wht Is Required? You must determine which one of two given cids is more cidic. Wht Is Given? For one cid, the initil concentrtion is mol/l nd the is For the second cid, the initil concentrtion is mol/l nd the is Pln Your Strtegy Designte the first cid s HA 1. Write blnced eqution for the cid-dissocition of the first cid. Let represent the chnge in concentrtion in mol/l of HA 1 tht ionizes to rech equilibrium conditions. Using the stoichiometric reltionships in the blnced eqution nd the initil concentrtion of HA 1, set up n ICE tble for the equilibrium. Act on Your Strtegy See the ICE tble below. HA 1 (q) + H O(l) A 1 (q) + H 3 O+(q) [HA 1 (mol/l) [A 1 (mol/l) [H 3 O + (mol/l) I C + + E Write the epression for the rection. Substitute the equilibrium concentrtions nd the vlue of into the epression for. Re-rrnge the epression into qudrtic eqution. [H3O [A 1 [HA 1 [H3O [A 1 [HA 1 7 ( )( ) ( )( ) (0.045 ) = = = 0 19 MHR Chemistry 1 Solutions Mnul

10 Use the qudrtic formul to solve for. b b 4c Clculte the ph using the eqution ph = log [H 3 O +. Designte the second cid s HA. Write blnced eqution for the ciddissocition of the second cid. Let represent the chnge in concentrtion in mol/l of HA tht ionizes to rech equilibrium conditions. Using the stoichiometric reltionships in the blnced eqution nd the initil concentrtion of HA, set up n ICE tble for the equilibrium. b b c 4 (1) = or = ( ) (4)(1)( ) Becuse it is impossible to hve negtive concentrtion, cnnot equl Therefore, [H 3 O + = mol/l. ph = log [H 3 O + = log ( ) = 3.73 See the ICE tble below. HA (q) + H O(l) A (q) + H 3 O+(q) [HA (mol/l) [A (mol/l) [H 3 O + (mol/l) I C + + E Write the epression for the rection. Substitute the equilibrium concentrtions nd the vlue of into the epression for. [H3O [A [HA [H3O [A [HA ( )( ) Unit 4 Prt B MHR 193

11 Re-rrnge the epression into qudrtic eqution. Use the qudrtic formul to solve for. b b 4c Clculte the ph using the eqution ph = log [H 3 O +. Identify the cid hving the higher [H 3 O +. 8 ( )( ) (0.087 ) = = = 0 b b 4c (1) = or = ( ) (4)(1)( ) Becuse it is impossible to hve negtive concentrtion, cnnot equl Therefore, [H 3 O + = mol/l. ph = log [H 3 O + = log ( ) = 4.03 Acid HA 1 hs lower ph nd higher [H 3 O +. Check Your Solution The nswer for the concentrtion of [H 3 O + seems resonble for these vlues. 194 MHR Chemistry 1 Solutions Mnul