Download Name: CHAPTER 21 PRICE Physical Science: Guided Notes

Name: ________________________
Physical Science: Guided Notes
CHAPTER 21
PRICE
Chapter 21: Chemical Equations
Section 1: Chemical Change
What is a chemical reaction?
A. Describing a chemical reaction
1. ____________________ Reactions- change of one or more substances converted into new substances
2. Reactants - substances that __________________ or change
3. __________________- new substances that are produced
Produce:
Reactants ---- __________________
B. Conservation of Mass
1. Conservation of _____________-a law which states that, in a chemical reaction, ___________ is not created or ______________; it
stays the ___________
2. Antione Lavoisier – _________________ of Modern Chemistry
1. Found mass of __________________ equaled the mass of the reactants
C. Writing Equations
1. Chemical _______________ - uses chemical _________________ and _________________ to describe a chemical reaction and the
products it produces
2. ______________________ formula - expresses the ____________________ between elements in the compounds and molecules they
make up
3. _____________________ used to show physical state of reactants; (s) _______________ (aq) aqueous (g) _________ (l) liquid
4. _______________________ – whole numbers in ____________ of the symbol, which represent the number of ______________ of each
substance in a reaction **Located before the symbols
5. __________________________ – small lowered numbers which represent the number of atoms in a molecule of a particular
element
*Located after and _____________ the symbols
6. Nomenclature – way to name things scientifically
Discussion Questions
1. What does the law of conservation of mass state?
2.
What is the function of coefficients in a chemical equation?
Section 2: Chemical Equations: Checking for Balance
1. A _________________ chemical reaction- both sides of equation have the ___________ number of atoms of each element
2. Coefficients are used in _____________ of the element or compound to balance.
3. Choosing coefficients - becomes _____________ with practice; trial and error at first
Writing balanced chemical equations - 4 step process
1. ____________ the reaction in words
2. Write the equation using _________________ and symbols
3. Check for ______________
4. Add ________________ where needed for balance
Discussion Question
 Why do chemical equations need to be balanced?
Section 3: Classifying Chemical Reactions
Types of Reactions:
1. _________________ Reaction- two or ___________ substance form a new substance
A + B --> AB
2. Decomposition Reaction-One substance _________________ down into two or more substances
AB ---> A + B
3. __________________-displacement Reaction- one element _______________ another one in a compound;
A + BC ---> AC +B or D + BC --> BD + C
4. Double-displacement Reaction- results if a ______________________, water, or a gas forms when ___________ ionic
compounds in a solution are combined;
AB + CD --> AD + CB
5. Combustion Reaction-a substance ___________________ with oxygen to produce energy
“X” + O2 --> CO2 + H2O
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Oxidation-Reduction (Redox)
These reactions often involve oxygen
 _________________________
Loss of electrons
Substance ________________ “oxidized”
 Reduction
Gain of _________________
Substance becomes “reduced”
Discussion Questions
1. What two chemical reactions are “opposites” of each other and why?
2. What are the 5 types of chemical reactions?
Section 4: Chemical Reactions and Energy
Chemical Reactions ______________________ energy exchange
___________________-Breaking chemical bonds release energy
Endergonic-Forming chemical bonds requires _______________
____________________-Chemical Reaction where energy is primarily given ____________ in the form of heat
Endothermic-Chemical reaction that _________________ heat energy in order to proceed
B. More energy out
1. A catalyst speeds up a chemical reaction without itself being permanetly changed
2. An inhibitor prevents or slows a chemical reaction or interferes with the catalyst’s action
DISCUSSION QUESTIONS:
 How are chemical bonds involved in energy exchanges?
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