-shows chemical change-before & after picture of reactionMust have: 1)substances before arrow = reactants substances after arrow = products 2)Conservation Mass-Kind of elements & Number elements in reactants must equal products .:balance 3)Catalyst written above arrow.

ex/Hydrogen peroxide solution breaks down into water and oxygen gas in the presence of manganese dioxide catalyst.

2 H2O2(aq) 2 H2O(l) + O2(g)

ex/Silver nitrate solution when added to copper metal, produces silver metal and copper(II) nitrate.

Chemical Equations

Steps:1)Element-diatomic? Compound-ionic? or covalent?2)Balance the equation.

ex/Susan mixed Nitric acid with zinc metal. A gas cloud of hydrogen gas was released and a solution of zinc nitrate

remained.

Nitric Acid + Zinc → Hydrogen + Zinc Nitrate

2HNO3 + Zn → H2 + Zn(NO3)2

ex/John placed lead(II) sulfate solution and a zinc rod into a 250mL beaker. A solution of zinc sulfate and lead metal

form.

Writing Chemical Equations

Word Equation

Chemical Equation

4 Types:Synthesis Al(s) + O2(g) Al2O3(s)

Decomposition H2O(l) H2(g) + O2(g)

Single Replacement Zn(s) + Pb(NO3)2(aq) Pb(s) + Zn(NO3)2(aq)

Double Replacement BaCl2(aq) + Na2CO3(aq) BaCO3(s) + NaCl(aq)

Chemical Reactions

electrolysisElectrolysis-Chemical reaction in which you separate elements of a compound using electricity!

Others: (Involve Energy)Combustion

Complete Fuel + O2(g) CO2(g) + H2O(g)

Incomplete Fuel + O2(g) CO(g) + H2O(g)

Fuel + O2(g) C(s) + H2O(g)

Endothermic NH4NO3(s) NH4+

(aq) + NO3-(aq)

Exothermic CaCl2(aq) Ca+2(aq) + Cl-(aq)

Chemiluminescence NO(g) + O3(g) NO2*(g) + O2(g)

H20 (l)

H20 (l)

-metal replaces a metal-nonmetal replaces a nonmetal-sometimes they react and sometimes not, depends upon if most reactive metal or nonmetal is by itself!

ex/Zn + H2SO4 ZnSO4 + H2

Cl2 + NaBr

Sn + NaNO3

The first reaction was done for you. Which of the bottom 2 will not react? How can you tell?

Activity Series-reactive metals will replace less reactive metals in a compound. -reactive nonmetals will replace less reactive nonmetals in a compound.

active

Single Replacement Reactions

Barium

Complete the following Single Replacement Reactions using activity series:

Na + CaCl2

Mg + Ba(NO3)2

F2 + MgCl2

Cl2 + KI

Ag + Cu(NO3)2

Pb + Zn(NO3)2

Zn + Pb(NO3)2

Ionic Compound Solubility RulesCompounds of Group I elements & ammonium are aqueous.Compounds of ammonium are aqueous.Compounds of acetates are aqueous.Compounds of nitrates are aqueous.Compounds of Group 17 elements are aqueous unless they contain silver, mercury(I), or lead. All F compounds are aqueous.Compounds of sulfates are aqueous except barium, strontium, lead, calcium, silver, and mercury(I)Compounds of carbonate, hydroxide, oxide, sulfide, and phosphate are solids except Group I elements & ammoniumCompounds of chromates are solids except for Group I elements and Be, Mg, Ca, Sr.

Double Replacement Reactions-cmpd + cmpd cmpd + cmpd-must produce (s) or (g)-cannot have 2 (aq) products-use solubility rules pg821 insoluble=not soluble=solid

ex/AgNO3(aq) + NaCl(aq) AgCl(s) + NaNO3(aq)

ex/NaOH(aq) + BaCl2(aq)

K2SO4(aq) + Pb(NO3)2(aq)

Complete the following double replacement reactions using solubility rules:

CuCl2 + Pb(NO3)2 →

Ca(OH)2 + H3PO4 →

K2CO3 + LiNO3 →

FeBr3 + NaOH →

KNO3 + Na2SO4 →

AgC2H3O2 + K2CrO4 →

Ba(NO3)2 + K2SO4 →

Net Ionic Equations

-Ionic Equation

-Net Ionic Equation-exclude spectator ions

Redox Reactions-known about since the Greeks-”smelting of iron & copper”-involves elements gaining and losing electrons-used in industry to convert metals in an ion form(compound) into a pure element form-purifying ores and corrosion reactions-reduction--oxidation-

ex/smelting of iron

Fe2O3 + CO Fe + CO2

ex/smelting of tin

SnO2 + C Sn + CO2

ex/electroplating of copper

CuSO4 + Pb Cu + PbSO4

+6 -6 = 0+3 -2

+2 -2 = 0+2 -2

+4 -4 = 0+4 -20

Balancing Oxidation Reduction 1. Assign individual oxidation numbers to all elements in the equation.

2. Identify which elements are oxidized and which are reduced (which ones have different oxidation numbers) ---show both oxidation and reduction with arrows.

3. Start writing the half-reactions by “bringing down” only the atom/ions that have changed oxidation numbers. (Bring their oxidation numbers with them!) When “bringing down” atoms or ions to put in half-reactions, do not bring down subscripts unless you have diatomic or triatomic gasses to bring down. Do not bring down subscripts for any elements found in compounds.

4. Balance all major atoms/ions, before balancing electrons.

5. Balance the total charge on both sides of each half-reaction, by adding electrons(e-) as needed, to one side only.

6. Ensure that the numbers of electrons in all oxidation half-reactions are equal to the number of electrons in all reduction half-reactions. If they are not, multiply one or more of the half-reactions to force the number of electrons in the half-reactions to be equal.

7. Add the half-reactions together; I.e. left sides added together and right sides added. You should now be able to subtract the same number of electrons from both sides and eliminate the electrons completely.

8. Use the coefficients (for the oxidized and reduced elements) that result from the above steps and substitute them into the original equation. [Sometimes one of the coefficients may not work because of excess reactants involved.]

9. Finish balancing the total equation as necessary.

Please Note:[Sometimes H2O and/or H+ may appear on both sides of the equation in step #4 above. As usually done in Algebra, you can subtract the same number of either one from both sides to simplify the equation.] Sometimes it may also be necessary to balance H & O after you have written the coefficients. Since we usually consider that redox reactions are balanced in acid solutions, we can add H2O to an equation where oxygens are needed and compensate with H+ ions(acid) on the opposite side of the equation.

MRE DemonstrationHow does an MRE Packet-Meals Ready to Eat work???

 

  Mg + H2O Mg(OH)2 + H2 + heat

Mg + O2 MgO

MgO + Fe Fe2O3 + Mg

-heat speeds up the chemical reaction-catalyst lowers activation energy-MgO is broken back down into Mg-high surface are of Mg increases reaction rate-redox reaction

reduction

oxidation

Activation EnergyNaCl+2+10 0

Nuclear Radiation3 particles:-each has energy!!-each has different size

1)alpha-stopped by a sheet of paper/clothing -damage over short range only

4 He 2

2)beta-stopped by a sheet of aluminum foil-damage over short range and little damage over long range

0 e - -1

3)gamma-stopped by thick layers of lead and concrete -considerable damage all ranges

0 0

mass #

atomic #

Others:1)Proton 1 p

1

2)Neutron 1 n0

3)Positron 0 e + +1

Balancing Nuclear ReactionsGolden Rules:-Conservation of Matter-matter is neither created nor destroyed, it merely changes form!!-use the 6 particles: alpha, beta, gamma, protons, neutrons,positrons to balance the equation.

ex/ 14 C 14 N + 0 e 6 7 -1

229 Fr 225 At + 87 85

235 U 1 p + 92 1

+ 0 e 251 Cf -1

½ Life-”Radioactive Clock”-used by archeologists to determine age of ancient, past living objects: ex/bones, wood structures, fossils-use radioactive isotopes found in living organisms such as 14C and 34P-amount time needed for ½ substance to decay into another, more radioactively stable substance

Formulas:end mass = start mass 2# ½ lives

Start mass = end mass x 2# ½ lives

# ½ lives = decay time ½ life time

ex/If a sample contains 800,000atoms of 14C. How many atoms would remain after 56,000yrs? The ½ life for 14C=5730yrs.

ex/Tricia, an archeologist in Paris, France excavates an ancient lion. She sends off the jaw from the lion for dating analysis. The jaw should contain 20g of 14C just before the lion died. When tested, the object contained 0.62g of 14C. If the ½ life for 14C=5730yrs, when did the lion die?

Resourceshttp://www.accessexcellence.org/AE/AEC/CC/radio_table.html

http://www.lbl.gov/abc/