Electrochemistry Lesson 4 Using Oxidation Numbers Using Oxidation

  • Slides: 24
Download presentation
Electrochemistry Lesson 4 Using Oxidation Numbers

Electrochemistry Lesson 4 Using Oxidation Numbers

Using Oxidation Numbers If the oxidation number of the central atom increases going from

Using Oxidation Numbers If the oxidation number of the central atom increases going from left to right, its oxidation. +3 Increase is oxidation Cl. O 2 oxidation reducing agent 4 electrons lost +7 Cl. O 4 -

Using Oxidation Numbers If the oxidation number of the central atom decreases going from

Using Oxidation Numbers If the oxidation number of the central atom decreases going from left to right, its reduction. +5 decrease is reduction NO 3 - reduction 2 electrons gained oxidizing agent +3 HNO 2

Label the oxidizing agent and the reducing agent. +7 +1 +5 Re. O 4+

Label the oxidizing agent and the reducing agent. +7 +1 +5 Re. O 4+ IO- IO 3+ Reduced Oxidized Ox Agent Red Agent 0 Re

Label the oxidizing agent and the reducing agent. +3 +5 +5 +2 3 As

Label the oxidizing agent and the reducing agent. +3 +5 +5 +2 3 As 2 O 3 + 4 NO 3 - + 7 H 2 O + 4 H+ 6 H 3 As. O 4 + 4 NO oxidized reduced red agent ox agent

Predicting Spontaneous Reactions Using the Standard Reduction Chart Does Au 3+ react with Cl-?

Predicting Spontaneous Reactions Using the Standard Reduction Chart Does Au 3+ react with Cl-? If it does write the spontaneous reaction.

The top reaction is written forward- reduction The bottom reaction is written in reverse-

The top reaction is written forward- reduction The bottom reaction is written in reverse- oxidation 3+ + 3 e- Au ) (Au 2 (s) - Cl (2 Cl 3 2(g) + 2 e-) 2 Au 3+ + 6 Cl- 3 Cl 2(g) + 2 Au(s)

Does Ag+ react with Br-?

Does Ag+ react with Br-?

nonspontaneous

nonspontaneous

Some ions are on both sides of the table and are oxidizing or reducing

Some ions are on both sides of the table and are oxidizing or reducing agents. For example: Fe 2+ Fe 3+ Sn 2+ Sn 4+ Cu+ Cu 2+

Does Sn 2+ react with Cr?

Does Sn 2+ react with Cr?

Check both spontaneous (Sn 3 2+ + 2 e- Sn(s)) 3+ + 3 e-)

Check both spontaneous (Sn 3 2+ + 2 e- Sn(s)) 3+ + 3 e-) (Cr Cr 2 (s) 2 Cr (s) + 3 Sn 2+ 2 Cr 3+ + 3 Sn(s)

Can you keep HCl in a Cu container? Explain!

Can you keep HCl in a Cu container? Explain!

nonspontaneous

nonspontaneous

Can you keep HCl in a Cu container? Explain! Yes, nonspontaneous. H+ is a

Can you keep HCl in a Cu container? Explain! Yes, nonspontaneous. H+ is a weaker oxidizing agent than Cu 2+ and Cu+.

Can you keep HCl in a Zn container? Explain!

Can you keep HCl in a Zn container? Explain!

Spontaneous- no H+ is a stronger oxidizing agent than Zn 2+

Spontaneous- no H+ is a stronger oxidizing agent than Zn 2+

Write the spontaneous reaction. 2 H+ + 2 e- H 2(g) Zn(s) Zn 2+

Write the spontaneous reaction. 2 H+ + 2 e- H 2(g) Zn(s) Zn 2+ + 2 e 2 H+ + Zn(s) H 2(g) + Zn 2+

Can you keep HNO 3 in a Au container? Explain!

Can you keep HNO 3 in a Au container? Explain!

Can you keep HNO 3 in a Au container? Explain! Yes, nonspontaneous. HNO 3

Can you keep HNO 3 in a Au container? Explain! Yes, nonspontaneous. HNO 3 is a weaker oxidizing agent than Au 3+.

Can you keep HNO 3 in a Cu container? Explain!

Can you keep HNO 3 in a Cu container? Explain!

Take the strongest ox agent- higher Take the strongest red agent- lower

Take the strongest ox agent- higher Take the strongest red agent- lower

Can you keep HNO 3 in a Cu container? No, spontaneous. HNO 3 is

Can you keep HNO 3 in a Cu container? No, spontaneous. HNO 3 is a stronger oxidizing agent than Cu 2+. Write the spontaneous reaction. NO 3 - + 4 H+ + 3 e- NO(g) + 2 H 2 O Cu(s) 2 NO 3 - + Cu 2+ + 2 e 8 H+ + 3 Cu(s) x 2 x 3 2 NO(g) + 4 H 2 O + 3 Cu 2+