Study Guide- Chemical Reactions Test-December 17, 2014
Chemical Interactions Textbook pages (Chapter 1: Section 1, Section 2, Section 3): 14-21; 24-28; 32-37
Notebook pages:
Review Study guide/ Notes from Quiz 1- Chemical Reactions/Bonding, Logs of scientific terms (Chapter 1 section 1 and
section2)
Review the study guide Monday Dec. 15 :Review game on Tuesday December 16th. Extra help- during Flex, see me if
want to come in during lunch.
You will be able to use your periodic table book mark. You will NOT be permitted to go to your locker if you forget it the
day of the test.
Key Terms:
Ionic Bonds
Chemical Equations
Products
Covalent Bonds
Subscript
Law of Conservation of
Mass
Inhibitor
Synthesis
Catalyst
Temperature
Molecule
Coefficient
Exothermic Reaction
Compound
Reactants
Endothermic Reaction
Concentration
Decomposition
Surface Area
Replacement
Answer on separate sheet of paper:
1) Define Ionic and Covalent Bonds. What are the differences between them?
Ionic bonds transfer (valance) electrons between a metal and a non-metal during a chemical reaction. A covalent bond is
the sharing of (valence) electrons between two non-metals during a chemical reaction.
2) Name the 5 different types of evidence for chemical reactions.
Change in temperatureChange in properties- light or odor(smell) is given off, change in texture (cake batter (goopy ---> fluffy cake)
Change of color
Forms a solid (precipitate) during a chemical reaction
Gas production- which can be seen from fizzing or bubbling
3) Explain the difference between a molecule and a compound.
A molecule is when two or more atoms bond together
A compound is when two or more atoms combine chemically (bond) together in a specific ratio
4) Identify the coefficient and subscript in: 3CHCl3
Coefficient
3 CHCl3
subscript
5) What information is included in a chemical formula? In a chemical equation?
A chemical formula is a combination of chemical (element) symbols, (elements and subscripts that represent the
numbers of atoms in that element),that represent the number of elements in a compound.
A chemical equation is a combination of chemical formulas and coefficients, that show chemical reactions using symbols
instead of words.
6) Identify the reactants and products in: 2Mg + O2
Reactants
2MgO
Products
7) Explain the Law of Conservation of Mass by using the alka seltzer lab or the Lego activity to support your answer. How
does it explain why a chemical must be balanced?
Matter can not be created or destroyed in any physical or chemical change or reaction , the atoms are only rearranged
into something else. In the alka seltzer an Lego activity the mass of the reactants (before the reaction) equaled the mass
of the products (after the reaction). Chemical equations must be balanced in order to follow this principle. The total
number of elements on the reactants must equal the total number of elements in the products side of the equation.
8) What is the difference between an exothermic reaction and endothermic reaction?
An exothermic reaction releases energy in the form of heat during a chemical reaction- producing heat energy (is
warmer/hotter).
Examples: Birthday candles burning, explosions, hand warmers, gasoline burning
An endothermic reaction absorbs or takes in energy during a chemical reaction, the products are cooler/ colder
Examples: Instant ice packs, baking soda mixing with vinegar, the reaction TAKES heat from the solution, making it
feel colder.
9) What is the difference between a catalyst and inhibitor? When would a scientist use them?
A catalyst increases the rate (speed) of a reaction by lowering the amount of energy needed to start the reaction.
They help with the reaction , but are considered apart of the reaction itself, so it would not be considered a reactant
and would not be in the products.
An Inhibitor- is used to decrease the rate of a reaction.
Scientists would use a catalyst when they want to speed up a reaction, but do not want to change the reactants in the
chemical reaction. Because Catalyst can speed up a reaction, but are not changed in the reaction itself.
Scientists would use an inhibitor when they want to slow down a reaction or delay the energy released from a reaction.
10) List and describe the three ways to change the rate of chemical reactions. (Do not need to be word for word with my
responses)
Concentration- is the amount of one material in a given volume of another material. Ex: adding a spoon full of sugar
to a glass of lemonade would make it more sweet then a glass of lemonade with no sugar. More sugar makes the
lemonade has a greater concentration of sugar molecules. If a material is more concentrated than it has more molecules
to be reacted with during a chemical reaction, making the reaction happen faster.
Surface area- The more particles of a material that are exposed means there is more that can be reacted with, so the
reaction happens faster. Example suttign the cubes in class, the more the cube was cut, the more sides that were
exposed. Chewing your food more breaks it into smaller pieces giving more surfaces exposed to be reacted with in your
stomach, digestion would happen faster.
Temperature- Heating a substance makes particles move faster, cooling molecules makes them move slower. Faster
moving particles increases the rate of reactions. They come in contact more often, so there are more chances for a
reaction to happen and they have more energy to get over the (activation) energy "hump."
11) Be able to identify if an equation is balanced or unbalanced. (Don’t forget to write the number of atoms first!)

NH3 + 3O22
1N 3H 6,O

NaCl + H2SO4
1Na, 1Cl, 2H, 1S, 4,O

Mg
1Mg

+ 2HCl
2H, 2Cl
Ag + H2S
1Ag 2H, 1S
N2 + 6H20
4N
12H 6,O
Unbalanced
NaHSO4
+ HCl
1Na, 1H, 1S 4,O 1H 1Cl
Mg Cl2
+
1Mg, 2Cl
Ag2S +
2 Ag, 1S
H2
2H
H2
2H
Balanced
Balanced
Unbalanced
12) Balance the equations below: remember to follow the steps discussed in class and from the sample problem on pg.
29 in your textbook
1.Write the chemical equation (if not already written)
2. Count and write the number of atoms for each element in each of the
chemical formulas in the chemical equations.
(Don’t forget to include the chemical symbol along with it. Remember to multiply the
coefficients with the subscripts, no subscript means there is a subscript of 1).
3. Choose a coefficient(s) that will correctly balance the equation. (Recount the
atoms for each side) Is it balanced, if not try again with new coefficient
4. Rewrite the new equation with the new coefficient


_2_Na + F2
2 H2O +

C

2H + Cl2
+ 2Cl2
2 NaF
2H2 + O2
CCl4
2HCl
Using your knowledge about endothermic and exothermic reactions, look over the diagrams below, and
identify which represents the behavior of energy for an endothermic reaction and which represents the
behavior for energy for exothermic reaction and give a reason for your choice.
13.Exothermic, because the reaction is
14. Endothermic because the reaction is absorbing or
releasing, giving out energy during the
or taking in energy during the reaction, the product
reaction. The product is warmer/hotter after
is cooler/colder after the reaction.
the reaction.
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