Sub Packet Answer Keys
Monday, 9/28/15
The Science of Fireworks:
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B
C
D
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B
A
A
Eureka! Density!
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Scientists
Measure
Mathematician
Pure
Equal
Finding
Equivalent
Mass
Spilled
Discovery
Buoyancy
Iceberg
Hypothesis
Found
Scientific
Method
Scientist
Density Puzzle
Box Color
Red
Green
Blue
Yellow
Purple
Mass
72 g
24 g
73 g
35 g
46 g
Volume
144 cm3
32 cm3
69 cm3
25 cm3
16 cm3
Density
0.5 g/cm3
0.75 g/cm3
1.058 g/cm3
1.4 g/cm3
2.875 g/cm3
Tuesday, 9/29/15
AC SCIENCE – 3RD
SECTION 14.1: FORMING NEW SUBSTANCES
1. Sample answer: In one class of chemical reaction, two liquids are mixed, and a solid precipitate forms.
2. A
3. no
4. No; this is a physical change: the steam that is being formed is just another form of water.
5. Charcoal burning in a grill is chemical change because when charcoal burns, other substances form.
6.Formation of gas and light are clues that a chemical reaction is taking place.
7. Bonds in the starting substances are being broken.
SECTION 14.2: CHEMICAL FORMULAS AND EQUATIONS
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equation
products
D
B
a. CH4 + 2O2 → 2H2O + CO2
b. 3Mg + N2 → Mg3N2
6. There is the same number of atoms of each element on each side of the equation.
7. A subscript shows the number of atoms of a particular element that are present in a certain compound. A
coefficient is a number that is placed in front of a chemical symbol or formula in order to balance a chemical
equation.
8. 2Na3PO4:
6 atoms Na
2 atoms P
8 atoms O
4Al2(SO4)3:
8 atoms Al
12 atoms S
48 atoms O
6 PCl5:
6 atoms P
30 atoms Cl
9. To write a formula for a covalent compound, use the prefixes in the name of the compound to find how many
atoms of each element are in the compound. Use subscripts to indicate how many atoms of each element are
present.
10. The subscript in a formula cannot be changed when balancing an equation because that would change the
identity of the substance.
HS SCIENCE – 4TH, 5TH, 6TH
SECTION 14.3: TYPES OF CHEMICAL REACTIONS
1.Sample answer: A synthesis reaction is a reaction in which atoms are joined together to form a larger
molecule. A decomposition reaction is a reaction in which a compound is split apart to form simpler
compounds.
2. B
3. In a single-displacement reaction, one kind of atom moves from one compound to another. In a doubledisplacement reaction, two different kinds of atoms exchange places between compounds.
4. 2KI + Cl2 → 2KCl + I2
5. Calcium is more reactive than aluminum, so no reaction will take place.
6. The reaction is a double-displacement reaction: you started with two solid compounds, each of which must have
at least two types of atoms, and ended up with another solid compound, so two different types of atoms must
have switched places.
SECTION 14.4: ENERGY AND RATES OF CHEMICAL REACTIONS
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endothermic
inhibitor
C
A higher concentration increases the reaction rate.
An exothermic reaction gives off energy; an endothermic reaction absorbs energy.
Chewing food grinds it into smaller particles, which allows more surface area of the food to come into contact
with digestive juices.
7. an exothermic reaction; You can tell that energy has been given off because the reactants have a higher energy
than the products have.
8. The spike in the middle would not be as tall.
Wednesday, 9/30/15
Word Search Words
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Length
Volume
Ruler
Alloy
Chemiccal Symbol
Brittleness
Condensation
Balance
Heat
Fusion
Density
Mass
Size
Proton
Physical Change
Hydroelectric
Tape Measure
Texture
Property
Reactivity
Boiling Point
Observation
Turbines
Temperature
Periodic Table
Buoyancy
Viscosity
Combustibility
Physical property
Water Vapor
Gas
Evaporation
Freezing Point
Sound
Stickiness
Gravity