good morning ladies!

Good Morning Ladies!

1. Questions before the test?2. TEST

In both fission and fusion reactions, energy is…

RELEASED

because…

E = mc2

Energy = mass x speed of light squared

Mass is converted to energy

100 g samples of both radium-226 and radon-222 were left in a chemical laboratory in 1950. Which sample poses the least risk today?

Half-life of radium-226 is 1600yHalf-life of radon-222 is 3.82d

• radon-222 because it has a shorter half-life

• radon-222 because it decays faster

Good Afternoon Ladies!

1. Questions before the test?2. TEST

…………….

3. Begin Oxidation-Reduction Reactions Unit

In both fission and fusion reactions, energy is…

RELEASED

because…

E = mc2

Energy = mass x speed of light squared

Mass is converted to energy

100 g samples of both radium-226 and radon-222 were left in a chemical laboratory in 1950. Which sample poses the least risk today?

Half-life of radium-226 is 1600yHalf-life of radon-222 is 3.82d

• radon-222 because it has a shorter half-life

• radon-222 because it decays faster


• Prayer• Regents Review Resources• Begin Oxidation-Reduction Reactions Unit

– What are oxidation-reduction reactions?– Assigning oxidation numbers

HW: Redox 1 DUE MONDAY

Also: Simulating Half-Life Lab DUE next Friday

Oxidation-Reduction Reactions

*What kind of chemical reaction is responsible for burning, rusting, bleaching clothes, powering your cell phone as well as your body, and giving fireflies their glow?

• Oxidation-Reduction Reactions, also called REDOX reactions

I. What are Redox Reactions?

• Redox reactions involve the transfer of ELECTRONS (e–) between different atoms

Na + Cl → Na + Cl

Oxidation Reduction

* CONSERVATION OF CHARGE: oxidation and reduction happen simultaneously (at the same time) – you can’t have one without the other

Remember: LEO the lion says GER (or LEO the liger says GER)

• LOSING ELECTRONS is OXIDATION• GAINING ELECTRONS is REDUCTION


• Determining if a reaction is redox• Assigning oxidation numbers

HW: Redox 1 DUE MONDAY

Also: Simulating Half-Life Lab DUE next Friday

II. Determining if a reaction is a redox reaction

• If the oxidation number/state of an atom changes from reactant to product, a redox reaction has occurred

*Note: Double replacement reactions are NOT redox reactions

A. Assigning Oxidation Numbers(listed on the Periodic Table)

1. If a species is all by itself (not combined with a different element), its oxidation number is ZERO

Ex: Mg O2 S2 Cu H2

2. In a polyatomic ion, the elements’ oxidation numbers add up to equal the CHARGE on the ion

* SOS: you must multiply the Subscript by the Oxidation number to get the Sum

NH4+ ClO–


2. In a polyatomic ion, the elements’ oxidation numbers add up to equal the CHARGE on the ion


SO3 2– SO4 2–


3. In a compound, the oxidation numbers of the elements add up to ZERO (compounds are neutral)


NaCl



• SOS: you must multiply the Subscript by the Oxidation number to get the Sum

NH4Cl



• SOS: you must multiply the Subscript by the Oxidation number to get the Sum

H2SO3


More Examples

a.) What is the oxidation number of chlorine in iron (III) chloride?

More Examples

b.) What is the oxidation state of chromium in potassium chromate?

B. Checking for Changes in Oxidation Numbers

2 Na (s) + Cl2 (g) → 2NaCl (s)

• The oxidation # on Na changes from 0 to +1• Na loses electrons• Na is oxidized• Na is the reducing agent

• The oxidation # on Cl changes from 0 to –1• Cl gains electrons• Cl is reduced• Cl is the oxidizing agent

B. Checking for Changes in Oxidation Numbers

2Mg (s) + O2 (g) → 2MgO (s)

• The oxidation # on Mg changes from 0 to +2• Mg loses electrons• Mg is oxidized• Mg is the reducing agent

• The oxidation # on O changes from 0 to –2• O gains electrons• O is reduced• O is the oxidizing agent

Orange Packet

• #s 1, 21, 23, 25


• Prayer• Review Videos on Wikispace!• Trade & Grade Redox 1 (collect)• Writing Oxidation & Reduction Half-Reactions

HW: Redox 2 DUE WEDNESDAYReminder: Simulating Half-Life Lab DUE FRIDAY


• Review Videos on Wikispace!• Trade & Grade Redox 1 (collect)• Writing Oxidation & Reduction Half-Reactions

HW: Redox 2 DUE WEDNESDAYReminder: Simulating Half-Life Lab DUE FRIDAY

a.) Zn + 2HCl → ZnCl2 + H2

b.) 4Al + 3O2 → 2Al2O3

c. For soldiers on the front lines or on special remote missions, a hot meal can make a big difference. Instead of building a fire or carrying a stove with them, soldiers simply break open a bag and mix some magnesium metal with water to heat their food. This reaction is an example of a redox reaction, producing magnesium hydroxide, hydrogen gas, and heat as products. In the space below, write the oxidation and reduction half-reactions.

Whiteboard Practice

Write the oxidation and reduction half-reactions for the following redox reactions

Zn + HNO3 Zn(NO3)2 + NO2 + H2O

Sn + HNO3 + H2O H2SnO3 + NO

NaClO + H2S NaCl + H2SO4

Orange Packet

#s 2, 3, 19, 20, 22, 24, 26-30, 32-35

Good Morning Ladies! (TUES)

• Prayer• Gummy Bear Sacrifice• Breathalyzer Demo• Balancing Redox Reactions• Pass back Nuclear Chemistry Test

HW: Redox 2 DUE TOMORROWReminder: Simulating Half-Life Lab DUE FRIDAY

In the presence of oxygen, iron forms iron (III) oxide, more commonly known as rust. In the space below, write the balanced equation for the chemical process of the corrosion of iron using the oxidation and reduction half-reaction method.

What causes fruit to turn brown?

• Oxidation of compounds in fruit after exposure to oxygen in the air causes a change of color (browning) of fruit

Oxidation (losing electrons) is a process that can be very damaging to living things.

• results in the creation of free radicals, which are chemical species that have unpaired electrons (they are unhappy – they don’t have a completed valence shell)

• free radicals will rip electrons away from other compounds in living things, such as proteins or molecules of DNA, causing damage which can lead to cancer

• Antioxidants get rid of free radicals – Vitamins A, C, and E are antioxidants

Good Morning Ladies! (WED)

Please place your Redox 2 HW in the bin• Prayer• Two Types of Electrochemical Cells

– Voltaic cells– Electrolytic cells

Reminder: Simulating Half-Life Lab DUE FRIDAYHeads up HW: Redox 3 DUE TUESDAY*Redox Unit TEST next WEDNESDAY

Good Afternoon Ladies! (WED)

Please place your Redox 2 HW in the bin• Two Types of Electrochemical Cells

– Voltaic cells– Electrolytic cells

Reminder: Simulating Half-Life Lab DUE FRIDAYHeads up HW: Redox 3 DUE TUESDAY*Redox Unit TEST next WEDNESDAY

V. Electrochemical CellsA. Use REDOX reactions to convert chemical

energy into electrical energy OR convert electrical energy into chemical energy

1. Voltaic (Galvanic) Cells = batteries

a.) SPONTANEOUS redox reactions – NO energy put in (energy is released)

Use Table J to determine what is oxidized and what is reduced

Higher on Table J is OXIDIZEDLower on Table J is REDUCED

*Parts to Know*Electrodes: the places where oxidation or

reduction happensoAnode: the site of oxidation (An Ox)oCathode: the site of reduction (Red Cat)

Wire: electrons flow through the wire from the anode (–) to the cathode (+)

Salt bridge: allows IONS to flow between the electrodes to keep the charges balanced

The electrodes must be separated in order to produce an electric current (flow of electrons).

The energy present in the flowing electrons (ELECTRICITY) is captured and used to power other processes.

b.) Diagram of a voltaic cell using Zn and Zn(NO3)2

with Cu and Cu(NO3)2

c.) Voltaic cell problems:1. Look on Table J and find which element is higher

– this element is OXIDIZED (On Table J – electrons flow DOWNHILL,

spontaneously)2. Under each beaker write “oxidation” or “reduction”3. Label the oxidation electrode ANODE (An Ox)4. Label the reduction electrode CATHODE

(Red Cat)

5. Place a (–) charge on the anode6. Place a (+) charge on the cathode

7. Draw in the direction of electron flow (from ANODE (–) to CATHODE (+))

8.Write the half reactions under the correct beakers

9.Be able to describe what is occurring at the anode and cathode

10. The salt bridge allows for ions to flow between the electrodes

Positive (+) ions flow toward the CATHODE (to balance the negative electrons)

Negative (–) ions flow toward the ANODE (to replace the electrons that are leaving)

How many of you have had cavities filled?…if you do, you have the potential to make a tiny battery IN YOUR MOUTH!

• Cavities are filled with a mixture of metals including zinc (Zn), tin (Sn), copper (Cu), and silver (Ag)

• If you bite down on a piece of aluminum foil, the saliva in your mouth, the aluminum foil, and the filling make a little voltaic cell that produces a tiny current that travels through your tooth to the nerve below the filling…it’s a bit UNPLEASANT!

Voltaic cell animation

• http://www.blackgold.ab.ca/ICT/Division4/Science/Div.%204/Voltaic%20Cells/demo.htm

http://www.blackgold.ab.ca/ICT/Division4/Science/Div.%204/Voltaic%20Cells/demo.htm

http://www.blackgold.ab.ca/ICT/Division4/Science/Div.%204/Voltaic%20Cells/demo.htm

Orange Packet

#s 4-12, *16, 36, 37, 39

2. Electrolytic Cells

a.) NONSPONTANEOUS redox reactions – need to put in energyb.) The species more likely to lose electrons is forced to gain electrons

(On Table J – electrons are moving UPHILL, nonspontaneously)

2. Electrolytic Cells

c.) Electrons still flow from the anode to the cathode, but now the signs are reversed• The anode is (+) and the cathode is (–)

(electrons are being forced to travel to the negative electrode)

2. Electrolytic Cellsd.) Used for

1. Electrolysis: using electricity to break apart (lyse) compounds into their elements

Ex: Obtaining active elements from compounds

2NaCl (l)


1. Electrolysis: using electricity to break apart (lyse) compounds into their elements

Ex: Obtaining active elements from compounds

2H2O (l)


2. Electrolytic cells can also be used for electroplating – putting a metal coating on something

Anode:

Cathode:

Comparing & Contrasting Voltaic and Electrolytic Cells

Voltaic Cells (Batteries) Electrolytic Cells)

• SPONTANEOUS redox rxn

• energy is produced (electricity)

• anode is (-)• cathode is (+)

• nonspontaneous redox rxn

• energy is needed (needs electricity)

• anode is (+)• cathode is (-)

Comparing & Contrasting Voltaic and Electrolytic Cells

Voltaic Cells (Batteries) Electrolytic Cells)

• redox reactions• anode is where oxidation happens

(An Ox)• anode loses mass

• cathode is where reduction happens (Red Cat)

• cathode gains mass• electrons flow through wire

from anode to cathode

Orange Packet

#s 13-15, *17, *18, 38, 40-61

Bioluminescence vs. Fluorescence

• External energy source excites electrons

• Spectral lines

• UV light

• Redox reaction produces excited electrons

demos

• CuSO4 in Zn• Hydrolysis of water

good morning ladies!

Documents

elements oxidation numbers

oxidation numberstate

oxidation numberslisted

fusion reactions

shorter halflife radon

halflife of radium

d radon

redox reactionif