Chapter 21 electrochemistry

Chapter 21 electrochemistry - 21 Chapter Electrochemistry:...

Info iconThis preview shows pages 1–3. Sign up to view the full content.

View Full Document Right Arrow Icon

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: 21 Chapter Electrochemistry: Chemical Change and Electrical Work 21.1 Oxidation is a loss of electron( s ) and an increase in oxidation number. Reduction is a gain of electron( s ) and a decrease in oxidation number. 21.2 An electrochemical process involves an electron flow. At least one substance must lose electron( s ) and one substance must gain electron( s ) to produce the flow. This electron transfer is a redox process. 21.3 No. Oxidation is always accompanied by reduction. Electrons cannot be created or destroyed, only transferred. 21.4 O 2- is too strong a base to exist in H 2 O. The reaction O 2- + H 2 O B 2OH- occurs. Only species actually existing in solution can be used to balance an equation. 21.5 Multiply each half-reaction by the appropriate integer to make e- lost equal to e- gained. 21.6 Add an equal number of OH- ions to both sides to neutralize H + ions and produce H 2 O. 21.7 No. Add spectator ions to the balanced ionic equation to obtain the balanced molecular equation. 21.8 A voltaic or galvanic cell has a ∆ G sys < 0. An electrolytic cell has a ∆ G sys 0, meaning an increase in free energy. 21.9 a) True. b) True. c) True. d) False. In a voltaic cell, the system does work on the surroundings. e) True. f) False. The electrolyte in a cell provides a solution of mobile ions to maintain charge neutrality. 21.10 16H + ( aq ) + 2MnO 4- ( aq ) + 10Cl- ( aq ) B 2Mn 2 + ( aq ) + 5Cl 2 ( g ) + 8H 2 O( l ) a) Cl- b) MnO 4- c) MnO 4- d) Cl- e) From Cl- to MnO 4- f) 8H 2 SO 4 ( aq ) + 2KMnO 4 ( aq ) + 10KCl( aq ) B 2MnSO 4 ( aq ) + 6K 2 SO 4 ( aq ) + 5Cl 2 ( g ) + 8H 2 O( l ) 21.11 2 CrO 2- ( aq ) + 2 H 2 O( l ) + 6 ClO- ( aq ) B 2 CrO 4 2- ( aq ) + 3 Cl 2 ( g ) + 4 OH- ( aq ) a) CrO 2- b) ClO- c) ClO- d) CrO 2- e) from CrO 2- to ClO- f) 2 NaCrO 2 ( aq ) + 6 NaClO( aq ) + 2 H 2 O( l ) B 2 Na 2 CrO 4 ( aq ) + 3 Cl 2 ( g ) + 4 NaOH( aq ) 21.12 a) ClO 3- ( aq ) + 6I- ( aq ) + 6H + ( aq ) B Cl- ( aq ) + 3I 2 ( s ) + 3H 2 O( l ) oxidizing agent: ClO 3- ; reducing agent: I- b) 2MnO 4- ( aq ) + 3SO 3 2- ( aq ) + H 2 O( l ) B 2MnO 2 ( s ) + 3SO 4 2- ( aq ) + 2OH- ( aq ) oxidizing agent: MnO 4- ; reducing agent: SO 3 2- c) 2MnO 4- ( aq ) + 5H 2 O 2 ( aq ) + 6H + ( aq ) B 2Mn 2 + ( aq ) + 5O 2 ( g ) + 8H 2 O( l ) oxidizing agent: MnO 4- ; reducing agent: H 2 O 2 21.13 a) 3O 2 ( g ) + 4NO( g ) + 2H 2 O( l ) B 4NO 3- ( aq ) + 4H + ( aq ) oxidizing agent: O 2 ; reducing agent: NO b) 2CrO 4 2- ( aq ) + 8H 2 O( l ) + 3Cu( s ) B 2Cr(OH) 3 ( s ) + 3Cu(OH) 2 ( s ) + 4OH- ( aq ) oxidizing agent: CrO 4 2- : reducing agent: Cu c) AsO 4 3- ( aq ) + NO 2- ( aq ) + H 2 O( l ) B AsO 2- ( aq ) + NO 3- ( aq ) + 2OH- ( aq ) oxidizing agent: AsO 4 3- ; reducing agent: NO 2- ....
View Full Document

This note was uploaded on 01/21/2010 for the course CHEM 1A taught by Professor Kobiashi during the Spring '07 term at Ventura College.

Page1 / 28

Chapter 21 electrochemistry - 21 Chapter Electrochemistry:...

This preview shows document pages 1 - 3. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online