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Mass CANNOT be created nor destroyed.
In chemical reaction: the mass of the reactants
equals the mass of the products.
Reactants: starting materials
Products: new materials
Arrow: “goes to form” or “yields”
Coefficients: # in front of formula
Example:
Iron + oxygen iron (III) oxide
4 Fe(s) + 3 O2(g) 2 Fe2O3(s)
1. Count up the number of atoms on the
reactants side and products side.
2. Insert coefficients in front of the chemical
formulae until you have equal numbers of
atoms on each side.
3. Remember:
start with atom that appears in only 1
formula on each side first.
lowest common multiple rule for coefficients
keep polyatomic ions together.
To balance combustion reactions
ie: CxHy + O2 CO2 + H2O
Balance H’s first, then C’s, then O’s last.
If oxygen has an ODD number on product side, add a “fraction /2” coefficient to the oxygen, THEN DOUBLE all compounds and elements on both sides of the equation!!
OR – put the odd coefficient number in front of oxygen on the reactant side and double all other coefficients.
Example: Predict the products:
a) ____CH4 + ____O2 ____CO2 + ____ H2O
b) ____ C2H6 + ____O2 ____CO2 + ____ H2O
c) ____ C5H12 + ____O2 ____CO2 + ____ H2O
A. Formation (Synthesis)
element + element compound
B. Simple Decomposition
compound element + element
C. Single Replacement
element + compound element + compound
D. Double Replacement
compound + compound compound + compound
E. Neutralization (Acid/Base)
acid + base salt + water
F. Combustion
CXHY + O2 CO2 + H2O
Element + Element Compound
Examples: 2Co(s) + 3F2(g) 2CoF3(s)
2Mg(s) + Cl2(g) Mg2Cl(s)
Compound Element + Element
Examples: Si2 (s) 2Si(s) + 2Br2(l)
2H2O(l) 2H2(g)+O2(g)
Element + Compound Element + Compound
Examples: Zn(s) + CuSO4(aq) Cu(s) + ZnSO4(aq)
Cl2(g) + 2NaBr(aq) 2NaCl(aq) + Br2(l)
NEW! NEW!
Compound + Compound Compound + Compound
Example: AgNO3(aq) + NaCl(aq) AgCl(s) + NaNO3(aq)
NEW! NEW!
When a acid and base mix together they
neutralize each other.
acid + base salt + water
Example: H3PO4 + 3NaOH Na3PO4 + 3H2O
Common uses:
1. Lemon juice to neutralize fish odor
2. Antacids - TUMS
3. pH test in swimming pool
4. Baking soda in refrigerator
Acids
1. taste sour
2. turn blue litmus red
3. react with metals
4. conduct electricity
5. neutralize bases
6. pH is less than 7
7. Most soluble in water
Bases
1. taste bitter2. turns red litmus blue3. feel slippery4. conduct electricity5. neutralize acids6. pH is more than 77. does not react with metals8. Variable solubility in water
CxHy + O2 CO2 + H2O
Example: C3H8(g) + 5O2(g) CO2(g) + 4H2O(g)
Combustion equations
What are some chemical processes that
surround our everyday lives?
Pharmaceuticals
Photography
Biochemistry
Medicine
Pharmacology
Environmental
science
What are some
chemistry-related careers?
Case Study: P. 278
Read as a class – discuss Question a-e, # 2,3,4
Chemistry Laboratory Activities
Testing properties of Substances
Additional activity add – color change and precipitate