Do Now Balance the following three equations using whole number coefficients: _HgO(s)  Hg(l) + O2(g) 2. NaF + Cl2  NaCl.

Do Now Balance the following three equations using whole number coefficients: _____HgO(s)  ____Hg(l) + ____O2(g) 2. ____ NaF + ____ Cl2  ____ NaCl + ____ F2 3. ____ Zn + ____ AgNO3  ____ Zn(NO3)2 + ____ Ag 4. When balancing a chemical equation, why can you change only coefficients and not subscripts?

By the end of this class period I will be able to…
Define and identify different types of oxidation-reduction reactions: synthesis, decomposition, single-replacement, and combustion

Tarnishing – What type of change?

Today’s Game Plan Do Now 10 minutes Types of Reactions 15 minutes
Oxidation Reduction and Oxidation Numbers 20 minutes Can I Have Your Oxidation Number?? Independent Practice Exit Ticket

Precipitation Acid Base Redox
Chemical Reactions Precipitation Acid Base Redox

Chemical Reactions Precipitation Acid Base Oxidation Reduction (Redox)
Redox Reactions Can Be Further Subdivided

Oxidation-Reduction (Redox) Reactions
a transfer of electrons takes place; metals reacting with nonmetals, nonmetals reacting with O2 as a product or reactant

Redox Reaction Types Synthesis Reactions Decomposition Reactions Single Replacement Reactions Combustion Reactions

Decomposition Reactions
A Compound Is Broken Down Into Two or More Elements or Other Smaller Compounds AB A + B The body farm: studying the science of decay The Forensic Anthropology Center, at the University of Tennessee, Knoxville, conducts research into the postmortem decomposition of the human body. At the Center scientists study how variations in temperature, exposure, humidity and other environmental conditions affect cadavers and body parts. Their research has helped improve investigators' ability to estimate time of death and to identify individuals from skeletal remains. The Center also maintains a collection of documented human skeletons and has developed software that uses data from thousands of skeletons. Statistics from the database give investigators baselines that help them estimate the race, sex, and stature of unidentified bodies.

The body farm: studying the science of decay
The Forensic Anthropology Center, at the University of Tennessee, Knoxville, conducts research into the postmortem decomposition of the human body. At the Center scientists study how variations in temperature, exposure, humidity and other environmental conditions affect cadavers and body parts. Their research has helped improve investigators' ability to estimate time of death and to identify individuals from skeletal remains. The Center also maintains a collection of documented human skeletons and has developed software that uses data from thousands of skeletons. Statistics from the database give investigators baselines that help them estimate the race, sex, and stature of unidentified bodies.

A + B AB Synthesis Reactions
Two or more substances combine to form ONE compound A + B AB

Single Replacement Reactions
Part of a Compound is Replaced by a Single Element AB + C CB + A AB + C AC + B

Always produces CO2 and H2O
Combustion Reactions A Compound or Element always reacts with O2 and produces a large amount of heat energy Always produces CO2 and H2O Ex: Methane Bubbles

How do you recognize a… Combustion reaction?
Single replacement reaction? Decomposition reaction? Synthesis reaction? Double replacement reaction? Draw a picture to represent each reaction. ex: double replacement:

Oxidation Reduction Reading!
Therefore, sodium is oxidized. Each chlorine atom gains one electron, forming a negative chloride ion, and is thus reduced. Whenever a metal reacts with a nonmetal to form an ionic compound, electrons are transferred from the metal to the nonmetal. So these reactions are always oxidation-reduction reactions where the metal is oxidized (loses electrons) and the nonmetal is reduced (gains electrons).

Oxidation Reduction Reactions (redox)
A transfer of electrons takes place.

CH4(g) + 2O2(g)  CO2(g) + 2H2O(g)
Assign charges to each element or ion in the following reactions… 2Na(s) + Cl2(g)  2NaCl(s) CH4(g) + 2O2(g)  CO2(g) + 2H2O(g) We will be able to determine oxidation numbers for an equation like this!!

To Get Started…What is an Oxidation Number??
Oxidation Number: the number of electrons an element must gain or lose to become stable (8 valence electrons) What are the oxidation numbers for the following elements when they are in a compound? F ____ Be____ O_____ S_____

Oxidation Numbers A system that is used to keep track of electrons that are transferred in redox reactions. Not all redox reactions are made up of ionic compounds. This is why this system is needed.

Assigning Oxidation Numbers…Rules
Rule #1: Uncombined element’s charge = 0 Examples: Na O2

Rule #2: An ion’s oxidation # = the normal ionic charge Examples: BaCl2

Rule #3: Fluorine in compounds always = -1 Examples: NF3

Rule #4: Oxygen usually = -2 Examples: NO NO2

Rule #5: Hydrogen with nonmetals = +1 Examples: HF CH4

Rule #6: The sum of the charges must = the overall charge on the substance Examples: NH4+

Assigning Oxidation States
Na O2 BaCl2 Al2S3 NF3 NO NO2 HF CH4 KMnO4 SO42- NH4+ NaOCl Assigning Oxidation States Uncombined element’s charge = 0 An ion’s oxidation # = the normal ionic charge Fluorine in compounds always = -1 Oxygen usually = -2 (except H2O2 = -1 & OF2 = +2) Hydrogen with nonmetals = +1 The sum of the charges must = the overall charge on the substance

CH4(g) + 2O2(g)  CO2(g) + 2H2O(g)
Now we can assign oxidation numbers to the second reaction to show that there is a transfer of electrons (redox). OIL RIG 2Na(s) + Cl2(g)  2NaCl(s) Oxidation Is Losing electrons Reduction Is Gaining electrons CH4(g) + 2O2(g)  CO2(g) + 2H2O(g) Oxidation = increase in charge (loss of electrons) Reduction = reduction in charge (gain of electrons)

Assign charges to each element in the following reaction, then identify which elements are being oxidized and reduced… Fe2O H2  2Fe + 3H2O

Want my Oxidation Number?
I will display a reaction on the board and an element. You will have 30 seconds to decide what the oxidation number is for the selected element Write your answer on your whiteboard!

CH4(g) + 2O2(g)  CO2(g) + 2H2O(g)

CH4(g) + 2O2(g)  CO2(g) + 2H2O(g)
+4

PbS(s) + 3O2(g)  2PbO(s) + 2SO2(g)
+2

PbS(s) + 3O2(g)  2PbO(s) + 2SO2(g)
+4

Want my Oxidation Number?
I will display a reaction on the board and an element. You will have 30 seconds to decide if that element is oxidized in the reaction or reduced in the reaction Write your answer on your whiteboard!

Is K oxidized or reduced?
2K + Cl2  2K+ + 2Cl- Oxidized

Is Br oxidized or reduced?
2Al(s) + 3Br2(l)  2AlBr3(s) Reduced

Is Mg oxidized or reduced?
Mg + 2 HCl  MgCl2 + H2 Oxidized

Assign charges to each element in the following reaction, then identify which elements are being oxidized and reduced… Sn + 2S  SnS2

Independent Practice Silently and Independently begin on tonight’s homework.

Do Now Balance the following three equations using whole number coefficients: _HgO(s)  Hg(l) + O2(g) 2. NaF + Cl2  NaCl.

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Do Now Balance the following three equations using whole number coefficients: _____HgO(s)  ____Hg(l) + ____O2(g) 2. ____ NaF + ____ Cl2  ____ NaCl.

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Presentation on theme: "Do Now Balance the following three equations using whole number coefficients: _____HgO(s)  ____Hg(l) + ____O2(g) 2. ____ NaF + ____ Cl2  ____ NaCl."— Presentation transcript:

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Do Now Balance the following three equations using whole number coefficients: _HgO(s)  Hg(l) + O2(g) 2. NaF + Cl2  NaCl.

Presentation on theme: "Do Now Balance the following three equations using whole number coefficients: _HgO(s)  Hg(l) + O2(g) 2. NaF + Cl2  NaCl."— Presentation transcript: