Top Banner
Starter Find the balanced redox equations for: 1)H 2 O 2 with MnO 4 - to Mn 2+ and O 2 2)Cr 2 O 7 2- with I 2 to give I - and Cr 3+ Extension: S 2 O 3 2- and I 2 to give I - and S 4 O 6 2-
37

Starter Find the balanced redox equations for: 1)H 2 O 2 with MnO 4 - to Mn 2+ and O 2 2)Cr 2 O 7 2- with I 2 to give I - and Cr 3+ Extension: S 2 O 3.

Jan 01, 2016

Download

Documents

Brett Stafford

aq e kaqc eright

e znszn2 aq

e cureduction

e znse

electrode negative

electrode reactions

electrode positive

standard cell potential

Welcome message from author
This document is posted to help you gain knowledge. Please leave a comment to let me know what you think about it! Share it to your friends and learn new things together.
Transcript
Page 1: Starter Find the balanced redox equations for: 1)H 2 O 2 with MnO 4 - to Mn 2+ and O 2 2)Cr 2 O 7 2- with I 2 to give I - and Cr 3+ Extension: S 2 O 3.

Starter

Find the balanced redox equations for:1) H2O2 with MnO4

- to Mn2+ and O2

2) Cr2O72- with I2 to give I- and Cr3+

Extension:S2O3

2- and I2 to give I- and S4O62-

Page 2: Starter Find the balanced redox equations for: 1)H 2 O 2 with MnO 4 - to Mn 2+ and O 2 2)Cr 2 O 7 2- with I 2 to give I - and Cr 3+ Extension: S 2 O 3.

Starter

Find the balanced redox equations for:1) H2O2 with MnO4

- to Mn2+ and O2

MnO4¯ + 5e¯ + 8H+ —> Mn2+ + 4H2O(x2)

H2O2 ——> O2 + 2H+ + 2e¯ (x5)

2MnO4¯ + 5H2O2 + 6H+ —> 2Mn2+ + 5O2 + 8H2O

Page 3: Starter Find the balanced redox equations for: 1)H 2 O 2 with MnO 4 - to Mn 2+ and O 2 2)Cr 2 O 7 2- with I 2 to give I - and Cr 3+ Extension: S 2 O 3.

Starter

Find the balanced redox equations for:Cr2O7

2- with I2 to give I- and Cr3+

Cr2O72- + 14H+ + 6e¯ —> 2Cr3+ + 7H2O (x1)

½ I2 + e¯ —> I¯ (x6)

Cr2O72- + 14H+ + 3I2 —> 2Cr3+ + 6I ¯ +

7H2O

Page 4: Starter Find the balanced redox equations for: 1)H 2 O 2 with MnO 4 - to Mn 2+ and O 2 2)Cr 2 O 7 2- with I 2 to give I - and Cr 3+ Extension: S 2 O 3.

Starter

S2O32- and I2 to give I- and S4O6

2-

• 2S2O32- ——> S4O6

2- + 2e¯ (x1)

• ½ I2 + e¯ ——> I¯ (x2)

• 2S2O32- + I2 ——> S4O6

2- + 2I¯

Page 5: Starter Find the balanced redox equations for: 1)H 2 O 2 with MnO 4 - to Mn 2+ and O 2 2)Cr 2 O 7 2- with I 2 to give I - and Cr 3+ Extension: S 2 O 3.

Cell Potential

L.O.: Define the term standard electrode potential.Describe how to make an electrochemical cell. Calculate the standard cell potential of a cell.

Page 6: Starter Find the balanced redox equations for: 1)H 2 O 2 with MnO 4 - to Mn 2+ and O 2 2)Cr 2 O 7 2- with I 2 to give I - and Cr 3+ Extension: S 2 O 3.
Page 7: Starter Find the balanced redox equations for: 1)H 2 O 2 with MnO 4 - to Mn 2+ and O 2 2)Cr 2 O 7 2- with I 2 to give I - and Cr 3+ Extension: S 2 O 3.
Page 8: Starter Find the balanced redox equations for: 1)H 2 O 2 with MnO 4 - to Mn 2+ and O 2 2)Cr 2 O 7 2- with I 2 to give I - and Cr 3+ Extension: S 2 O 3.

• Homework

Page 9: Starter Find the balanced redox equations for: 1)H 2 O 2 with MnO 4 - to Mn 2+ and O 2 2)Cr 2 O 7 2- with I 2 to give I - and Cr 3+ Extension: S 2 O 3.
Page 10: Starter Find the balanced redox equations for: 1)H 2 O 2 with MnO 4 - to Mn 2+ and O 2 2)Cr 2 O 7 2- with I 2 to give I - and Cr 3+ Extension: S 2 O 3.

Electrode Potentials

know the IUPAC convention for writing half-equations for electrode reactions.

Know and be able to use the conventional representation of cells.

Know that standard electrode potential, E , refers to conditions of 298 K, 100 kPa and 1.00 mol dm−3 solution of ions.

Page 11: Starter Find the balanced redox equations for: 1)H 2 O 2 with MnO 4 - to Mn 2+ and O 2 2)Cr 2 O 7 2- with I 2 to give I - and Cr 3+ Extension: S 2 O 3.

Half-cell: an element in two oxidation states.

Page 12: Starter Find the balanced redox equations for: 1)H 2 O 2 with MnO 4 - to Mn 2+ and O 2 2)Cr 2 O 7 2- with I 2 to give I - and Cr 3+ Extension: S 2 O 3.

Zn2+(aq) + 2 e– Zn(s)

Page 13: Starter Find the balanced redox equations for: 1)H 2 O 2 with MnO 4 - to Mn 2+ and O 2 2)Cr 2 O 7 2- with I 2 to give I - and Cr 3+ Extension: S 2 O 3.

Zn2+(aq) + 2e¯ -> Zn(s) E° = - 0.76V

The electrode potential of the half cell indicates its tendency to lose or gain electrons.

Page 14: Starter Find the balanced redox equations for: 1)H 2 O 2 with MnO 4 - to Mn 2+ and O 2 2)Cr 2 O 7 2- with I 2 to give I - and Cr 3+ Extension: S 2 O 3.

The standard electrode potential of a half-cell, is the e.m.f of a cell compared with a standard hydrogen half-cell, measured at 298 K with a solution concentration of 1 mol dm-3 and a gas pressure of 100KPa

Page 15: Starter Find the balanced redox equations for: 1)H 2 O 2 with MnO 4 - to Mn 2+ and O 2 2)Cr 2 O 7 2- with I 2 to give I - and Cr 3+ Extension: S 2 O 3.

Standard Conditions

Concentration 1.0 mol dm-3 (ions involved in ½ equation)

Temperature 298 K

Pressure 100 kPa (if gases involved in ½ equation)

Current Zero (use high resistance voltmeter)

Page 16: Starter Find the balanced redox equations for: 1)H 2 O 2 with MnO 4 - to Mn 2+ and O 2 2)Cr 2 O 7 2- with I 2 to give I - and Cr 3+ Extension: S 2 O 3.

S tandard H ydrogen E lectrode

Page 17: Starter Find the balanced redox equations for: 1)H 2 O 2 with MnO 4 - to Mn 2+ and O 2 2)Cr 2 O 7 2- with I 2 to give I - and Cr 3+ Extension: S 2 O 3.
Page 18: Starter Find the balanced redox equations for: 1)H 2 O 2 with MnO 4 - to Mn 2+ and O 2 2)Cr 2 O 7 2- with I 2 to give I - and Cr 3+ Extension: S 2 O 3.

Zn

Zn Zn2+ + 2 e-

oxidation

Cu2+ + 2 e- Cureduction

- electrode

anodeoxidation

+ electrodecathode

reductionelectron flow

At this electrode the metal loses

electrons and so is oxidised to metal

ions.

These electrons make the electrode

negative.

At this electrode the metal ions gain

electrons and so is reduced to metal

atoms.

As electrons are used up, this makes the electrode positive.

Cu

Page 19: Starter Find the balanced redox equations for: 1)H 2 O 2 with MnO 4 - to Mn 2+ and O 2 2)Cr 2 O 7 2- with I 2 to give I - and Cr 3+ Extension: S 2 O 3.
Page 20: Starter Find the balanced redox equations for: 1)H 2 O 2 with MnO 4 - to Mn 2+ and O 2 2)Cr 2 O 7 2- with I 2 to give I - and Cr 3+ Extension: S 2 O 3.
Page 21: Starter Find the balanced redox equations for: 1)H 2 O 2 with MnO 4 - to Mn 2+ and O 2 2)Cr 2 O 7 2- with I 2 to give I - and Cr 3+ Extension: S 2 O 3.
Page 22: Starter Find the balanced redox equations for: 1)H 2 O 2 with MnO 4 - to Mn 2+ and O 2 2)Cr 2 O 7 2- with I 2 to give I - and Cr 3+ Extension: S 2 O 3.

Emf = E = E(positive

terminal) - E(negative terminal)

H2 at 100 kPa

o

o

o

o

o

o

o

o

o

o

o

o

salt bridge

1.0 M H+(aq)

Pt

temperature= 298 K

1.0 M Cu2+(aq)

V

Cu

high resistancevoltmeter

Page 23: Starter Find the balanced redox equations for: 1)H 2 O 2 with MnO 4 - to Mn 2+ and O 2 2)Cr 2 O 7 2- with I 2 to give I - and Cr 3+ Extension: S 2 O 3.
Page 24: Starter Find the balanced redox equations for: 1)H 2 O 2 with MnO 4 - to Mn 2+ and O 2 2)Cr 2 O 7 2- with I 2 to give I - and Cr 3+ Extension: S 2 O 3.
Page 25: Starter Find the balanced redox equations for: 1)H 2 O 2 with MnO 4 - to Mn 2+ and O 2 2)Cr 2 O 7 2- with I 2 to give I - and Cr 3+ Extension: S 2 O 3.

H2 at 100 kPa

o

o

o

o

o

o

o

o

o

o

o

o

salt bridge

1.0 M H+(aq)

Pt

temperature= 298 K

1.0 M Cu2+(aq)

V

Cu

high resistancevoltmeter

Pt(s) | H2(g) | H+(aq) || Cu2+(aq) | Cu(s)

Page 26: Starter Find the balanced redox equations for: 1)H 2 O 2 with MnO 4 - to Mn 2+ and O 2 2)Cr 2 O 7 2- with I 2 to give I - and Cr 3+ Extension: S 2 O 3.
Page 27: Starter Find the balanced redox equations for: 1)H 2 O 2 with MnO 4 - to Mn 2+ and O 2 2)Cr 2 O 7 2- with I 2 to give I - and Cr 3+ Extension: S 2 O 3.

Standard electrode potentials E/V

F2(g) + 2 e- 2 F-(aq) + 2.87

MnO42-(aq) + 4 H+(aq) + 2 e- MnO2(s) + 2 H2O(l) + 1.55

MnO4-(aq) + 8 H+(aq) + 5 e- Mn2+(aq) + 4 H2O(l) + 1.51

Cl2(g) + 2 e- 2 Cl-(aq) + 1.36

Cr2O72-(aq) + 14 H+(aq) + 6 e- 2 Cr3+(aq) + 7 H2O(l) + 1.33

Br2(g) + 2 e- 2 Br-(aq) + 1.09

Ag+(aq) + e- Ag(s) + 0.80

Fe3+(aq) + e- Fe2+(aq) + 0.77

MnO4-(aq) + e- MnO4

2-(aq) + 0.56

I2(g) + 2 e- 2 I-(aq) + 0.54

Cu2+(aq) + 2 e- Cu(s) + 0.34

Hg2Cl2(aq) + 2 e- 2 Hg(l) + 2 CI-(aq) + 0.27

AgCl(s) + e- Ag(s) + Cl-(aq) + 0.22

2 H+(aq) + 2 e- H2(g) 0.00

Pb2+(aq) + 2 e- Pb(s) - 0.13

Sn2+(aq) + 2 e- Sn(s) - 0.14

V3+(aq) + e- V2+(aq) - 0.26

Ni2+(aq) + 2 e- Ni(s) - 0.25

Fe2+(aq) + 2 e- Fe(s) - 0.44

Zn2+(aq) + 2 e- Zn(s) - 0.76

Al3+(aq) + 3 e- Al(s) - 1.66

Mg2+(aq) + 2 e- Mg(s) - 2.36

Na+(aq) + e- Na(s) - 2.71

Ca2+(aq) + 2 e- Ca(s) - 2.87

K+(aq) + e- K(s) - 2.93

Increasingreducing

power

Increasingoxidising

power

Page 28: Starter Find the balanced redox equations for: 1)H 2 O 2 with MnO 4 - to Mn 2+ and O 2 2)Cr 2 O 7 2- with I 2 to give I - and Cr 3+ Extension: S 2 O 3.

GOLDEN RULE

The more +ve electrode gains electrons

(+ charge attracts electrons)

Page 29: Starter Find the balanced redox equations for: 1)H 2 O 2 with MnO 4 - to Mn 2+ and O 2 2)Cr 2 O 7 2- with I 2 to give I - and Cr 3+ Extension: S 2 O 3.

Electrodes with negative emf are better at releasing electrons (better reducing agents).

Page 30: Starter Find the balanced redox equations for: 1)H 2 O 2 with MnO 4 - to Mn 2+ and O 2 2)Cr 2 O 7 2- with I 2 to give I - and Cr 3+ Extension: S 2 O 3.

• A2.CHEM5.3.003

5.3 EXERCISE 2 - electrochemical cells

Page 31: Starter Find the balanced redox equations for: 1)H 2 O 2 with MnO 4 - to Mn 2+ and O 2 2)Cr 2 O 7 2- with I 2 to give I - and Cr 3+ Extension: S 2 O 3.

Emf = Eright - Eleft

ELECTRODE POTENTIALS – Q1

- 2.71 = Eright - 0

Eright = - 2.71 V

Page 32: Starter Find the balanced redox equations for: 1)H 2 O 2 with MnO 4 - to Mn 2+ and O 2 2)Cr 2 O 7 2- with I 2 to give I - and Cr 3+ Extension: S 2 O 3.

Emf = Eright - Eleft

ELECTRODE POTENTIALS – Q2

Emf = - 0.44 - 0.22

Emf = - 0.66 V

Page 33: Starter Find the balanced redox equations for: 1)H 2 O 2 with MnO 4 - to Mn 2+ and O 2 2)Cr 2 O 7 2- with I 2 to give I - and Cr 3+ Extension: S 2 O 3.

Emf = Eright - Eleft

ELECTRODE POTENTIALS – Q3

Emf = - 0.13 - (-0.76)

Emf = + 0.63 V

Page 34: Starter Find the balanced redox equations for: 1)H 2 O 2 with MnO 4 - to Mn 2+ and O 2 2)Cr 2 O 7 2- with I 2 to give I - and Cr 3+ Extension: S 2 O 3.

Emf = Eright - Eleft

ELECTRODE POTENTIALS – Q4

+1.02 = +1.36 - Eleft

Eleft = + 1.36 - 1.02 = +0.34 V

Page 35: Starter Find the balanced redox equations for: 1)H 2 O 2 with MnO 4 - to Mn 2+ and O 2 2)Cr 2 O 7 2- with I 2 to give I - and Cr 3+ Extension: S 2 O 3.

Emf = Eright - Eleft

ELECTRODE POTENTIALS – Q5

a) Emf = + 0.15 - (-0.25) = +0.40 Vb) Emf = + 0.80 - 0.54 = +0.26 Vc) Emf = + 1.07 - 1.36 = - 0.29 V

Page 36: Starter Find the balanced redox equations for: 1)H 2 O 2 with MnO 4 - to Mn 2+ and O 2 2)Cr 2 O 7 2- with I 2 to give I - and Cr 3+ Extension: S 2 O 3.

Emf = Eright - Eleft

ELECTRODE POTENTIALS – Q6

a) Eright = +2.00 - 2.38 = - 0.38 V Ti3+(aq) + e- Ti2+(aq)

b) Eleft = -2.38 - 0.54 = - 2.92 V

K+(aq) + e- K(aq)c) Eright = - 3.19 + 0.27 = - 2.92 V Ti3+(aq) + e- Ti2+(aq)

Page 37: Starter Find the balanced redox equations for: 1)H 2 O 2 with MnO 4 - to Mn 2+ and O 2 2)Cr 2 O 7 2- with I 2 to give I - and Cr 3+ Extension: S 2 O 3.

ELECTRODE POTENTIALS – Q7

Emf = -0.76 - (-0.91) = +0.15 V

a) Cr(s) | Cr2+(aq) || Zn2+(aq) | Zn(s)

Emf = +0.77 - 0.34 = +0.43 V

b) Cu(s) |Cu2+(aq)|| Fe3+(aq),Fe2+(aq)| Pt(s)

Emf = +1.51 – 1.36 = +0.15 V

c) Pt(s) | Cl-(aq)| Cl2(g) || MnO4-(aq),H+(aq),Mn2+(aq)| Pt(s)


Related Documents
o o O o O cr cr Q€¦ · iTerrace:3 17 O o CD O CD . Created Date: 3/28/2014 11:19:56 AM

o o O o O cr cr Q€¦ · iTerrace:3 17 O o CD O CD ....

Category: Documents
$moZ H$mo nhMmZ cr{O`o

$moZ H$mo nhMmZ cr{O`o

Category: Documents
Torsten Beweries and Uwe Rosenthal O · wing to the fundamental rules of orbital symmetry, alkynes (RC≡CR), allenes (R 2 C=C=CR 2) and cumulenes (such as R 2 C=C=C=CR 2) are linear,

Torsten Beweries and Uwe Rosenthal O · wing to the...

Category: Documents
(Chemistry, Mathematics and Physics)...between O and H. Compound having no covalent bonds is KCl only. 16. The oxidation states of Cr in 23 66 6 2 ⎡⎤⎡ ⎤⎣⎦Cr H O Cl , Cr

(Chemistry, Mathematics and Physics)...between O and H....

Category: Documents
The Breathalyzer. The Breathalyzer The Breathalyzer Reaction C 2 H 5 OH+ Cr 2 O 7 2- + H + →CH 3 COOH+ Cr 3+ + H 2 O EthanolOrange AcidAcetic Acid Green.

The Breathalyzer. The Breathalyzer The Breathalyzer Reaction...

Category: Documents
Balancing Redox Reactions: Acid Conditions Balance the following redox equation: Cr 2 O 7 2- (aq) + HNO 2 (aq) --> Cr 3+ (aq) + NO 3 - (aq) (acidic) Oxidation.

Balancing Redox Reactions: Acid Conditions Balance the...

Category: Documents
S-72.3320 Advanced Digital Communication (4 cr) basics of... · Timo O. Korhonen, HUT Communication Laboratory 2 S.72-3320 Advanced Digital Communication (4 cr) Lectures: Timo O.

S-72.3320 Advanced Digital Communication (4 cr) basics...

Category: Documents
Catálogo de Baterías RC Microelectrónica, YUASA, VARTA ......CR 1/2 AA 3.0 950 25x14,75 CR 2/3 AA 3.0 1.350 33,5x14,75 CR 2/3 A 3.0 1.350 33,5x17 CR 2/3 AH 3.0 1.500 33,9x17 CR

Catálogo de Baterías RC Microelectrónica, YUASA, VARTA...

Category: Documents
A very warm welcome (Arial, 24-point bold font)...5 Fe Fe Fe Fe Fe FeC C Cr O2 O2 O2 FeFeOO FeFeOO O2 O 2 2 CFe Fe C Cr Cr O Cr O Proprietà – Resistenza alla corrosione Acciaio

A very warm welcome (Arial, 24-point bold font)...5 Fe Fe Fe...

Category: Documents
FYS3410 - Vår 2017 (Kondenserte fasers fysikk) · 3) + (0.5 to 2) at% Cr 2 O 3 -- Sapphire is transparent and colorless (E g > 3.1 eV) -- adding Cr 2 O 3: • alters the band gap

FYS3410 - Vår 2017 (Kondenserte fasers fysikk) · 3) +...

Category: Documents
Computador CR (2)

Computador CR (2)

Category: Documents
CHEMISTRY 1000 Topic #3: Colour in Chemistry Summer 2007 Dr. Susan Lait CdS Cr 2 O 3 TiO 2 Mn 3 (PO 4 ) 2 Co 2 O 3 Fe 2 O 3 Co 2 O 3 Cr 2 O 3 Cu 2 O UO.

CHEMISTRY 1000 Topic #3: Colour in Chemistry Summer 2007 Dr....

Category: Documents