Chapter 6 Section 2: Describing Chemical Reactions

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Chapter 6 Section 2: Describing Chemical Reactions
I.
What are chemical equations?
a. Is a short, ______ way to show a chemical __________, using
____________ instead of words.
b. Uses chemical formulas with ___________ and coefficients
to _______________ a reaction
i. A formula is a ______________ of symbols that
represents elements in the compound
ii. The substances at the ______ of the equation are called
_________, when the reaction is complete, on the right
you have ___________.
iii. If you have _____________ reactants or products they
are separated by a + ______
1. Reactant 1 + reactant 2 ----> Product 1 + product 2
2. See figures 7 and 8, page 195
II. Conversion of mass
a. During a chemical reaction, matter is ________________
nor destroyed, it just changes _______.
b. All the atoms __________ at the _______ of the reaction are
present at the ______
c. The principle of conservation of mass states that in a
chemical reaction, the ____________ of the reactants must
________ the total mass of the products
III. Open and closed systems
a. Open: matter can ______ from or ________ to the surroundings.
i. Burning match
b. Closed: matter is _____________ to enter or leave the system
i. Eg, reaction is sealed in a plastic bag
ii. See figure 10, page 197
IV. Balancing Chemical Equations
a. To describe a reaction _____________, a chemical equation
must show the _____________ of each type of _______ on
both sides of the equation
V.
b. 4 Step process
i. Step 1: Write the ____________: Reactants on the Left,
products on the right
1. ___H2 + ___O2 ----> ________H20
ii. Step 2: ________ the number of _______ of each element
on each side of the equation
1. 2 hydrogen, 2 oxygen on the react side, 1 oxygen
and 2 hydrogen on the product side. ____ THE
ATOMS __________ EQUAL GO TO STEP 3
iii. Step 3: Use ______________ to balance atoms
1. A coefficient is a ________ placed in _______ of a
chemical formula. It is ___________ by the subscript
to get the new number of atoms
2. Always check _______ sides when using a coefficient
3. 2H2 + 02 ----> 2H2O
iv. Step 4: ________ your work
Classifying Chemical reactions
a. Synthesis: when ____________ elements or compounds
combine to make a more ___________ substance
i. 2H2 + O2 ----> 2 H2O
b. Decomposition: _____________ compounds into simpler
products
i. 2H2O2 ----> 2H2O + O2
c. Replacement: When _____________ replaces another element
in a compound or when 2 elements in different compounds
________ places
i. 2CuO + C ----> 4 Cu + CO2
ii. FeS + 2 HCL ----> FeCL2 + H2S
iii. See figure 11, page 200
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