Unit 5 Chemical Reactions Chapter 8 Sec. 1. Objectives Indications of Chemical Reactions -How do you...
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Transcript of Unit 5 Chemical Reactions Chapter 8 Sec. 1. Objectives Indications of Chemical Reactions -How do you...
Unit 5
Chemical Reactions
Chapter 8Sec. 1
ObjectivesIndications of Chemical Reactions -How do you know a chemical reaction has happened?
Chemical Equations -How do you give/get information from a chemical equation
Balancing Equations -Matter is not created or destroyed
Chemical Reactions
To prove that one or more substances have undergone a change in identity...Need Chemical Analysis
BUT in the meantime
Observed Changes can strongly indicate a chemical reaction
Indications of a Chemical Reaction
1)Production of Heat2)Production of Light3)Production of a gas
4)Production of a precipitate
A solid that is produced in a chemical reaction and separates from solution
Vocab: Precipitate
Chemical Equations Represent the identities and relative amounts of reactants and products in a chemical reaction with symbols and formulas
Reactants Products “yield”
Chemical Equation ExampleZn(s) + HCl(aq) --> ZnCl2(aq) +
H2(g)
Reactants “yield” Products Zinc -solid
Hydrochloric Acid -aqueous solution
Zinc Chloride- aqueous solution
Hydrogen- gas
Important Symbols“yields” -indicates results
reversible reaction-can go both ways
(s)(l)
(aq)(g)
substance in the solid state substance in the liquid state
substance in the aqueous state (water solution)
substance in the gaseous state
heat
2 atm
0oC
MnO2
Reaction needs heat to get started
Reaction occurs at the pressure indicated
Reaction occurs at the temperature indicated
Reaction needs a catalyst to get started
Clean-Up This Mess!Zn(s) + HCl(aq) --> ZnCl2(aq) + H2(g)
ZnCl2(aq) + Na(OH)(aq) --> Zn(OH)(s) + NaCl(s) + H2O
Zinc Chloride + Sodium Hydroxide -->Zinc Hydroxide + Sodium Chloride + Water
Practice Word & Formula Equations
Methane + Oxygen --> Carbon Dioxide + Water
CH4(g) + O2(g) --> CO2(g) + H2O(l)
Predict the Products
“OMG! Where’d that 2 come from?!”
Memorize KNOW this...
The following elements exist as diatomic molecules:
Bromine= Br2 (l)
Chlorine= Cl2 (g)
Iodine= I2 (g)
Hydrogen= H2 (g)
Oxygen= O2 (g)
Fluorine= F2 (g)
When using ANY ofthe listed elements
in a chemical equation
USE AS DIATOMIC MOLECULES
“BrClHOFIN”
Other Common Formulas to Know
Water= H2OAmmonia = NH3Methane = CH4Carbon Dioxide = CO2Acids
Hydrochloric Acid = HCl
Hydrofluoric Acid = HF
Naming Compounds Review
Determine Compound Type
IonicM + NM Covalent
NM + NM
MetallicUse metal name
Ex: Zn = ZincCu2 = Copper
Transition Metal& Non Metal
Cation (Metal) & Anion (Nonmetal)
-Use prefixesEx: CO = carbon monoxideN2O2 = dinitrogen dioxide
-Use Reverse criss-cross method to determine charge on metal
-Use roman numerals to indicate that charge
Ex: Fe2O3 = Iron (III) Oxide
-Use criss-cross method to determine ratio of ion subscripts
Chemical Equations Cont.1) MUST show ALL reactants and
products
2) MUST contain correct formulas
3) MUST follow The Law of Conservation of Mass 4) MUST be BALANCED