Chemical Reactions Study Guide
Name: ____________________
Chemical Reactions
1.
List three or more signs you look for to determine if a chemical reaction has taken place.
Fizzing/bubbling, temperature change, color change, smell change,
2. How do you know that a chemical reaction has taken place?
A new substance with different properties is formed. Ex. Sodium + Chlorine = table Salt
3. Compare and contrast Endothermic and Exothermic reactions
Endothermic
Exothermic
Absorbs heat
Gives off heat
Temperatures go down (Endo=Down)
Temperatures go up
4. Identify each example as either Endothermic or Exothermic
Hand warmers giving off heat
Exothermic
Plants taking in light energy during photosynthesis
Endothermic
Logs burning in a fireplace
Exothermic
Water freezing into ice
Endothermic
Ice melting into water
Exothermic
5. What is a Catalyst? Give an example of one.
A Catalysts speeds up a reaction (think mushroom boost on Mario Kart.)
Ex. Room full of Hydrogen and Oxygen Gas (very flammable gasses) a match is struck which acts as the catalyst for
the combustion reaction.
6. How does a Catalyst speed up a chemical reaction?
It lowers the activation energy needed to start a reaction.
Chemical Equations
7. Fill in the chart.
Types of Reaction
Combustion
Synthesis
Decomposition
Definition
When oxygen (O2) combines with another compound to form water and carbon
dioxide. (*Boom  )
Two or more substances react to form a new substance(s)
One substance breaks down into two or more simpler substances
Single Replacement
One element replaces another element in a compound
Double Replacement
Elements from two different compounds switch places
8. Use lines to match the equations with the types of Chemical Reactions
Single Replacement
A + B  AB
Double replacement
ABC  AB + C
Synthesis
A + BC  AC + B
Decomposition
AB + CD  AC + BD
Chemical Formulas
9. For the following equations, Box-in the Products and Circle the Reactants
2NaCl → 2Na + Cl2
C2H4O2 + NAHCO3 → NAC2H3O2 + H2O +CO2
CaCl2 + 2NaHCO3 → CaCO3 + H2O + CO2
10. How many atoms of each element are in the following chemical formulas?
Example: 2H20 = Hydrogen= 4
Oxygen= 2
C6H12O6
2CH4
Carbon = 6, Hydrogen = 12, Oxygen = 6
Carbon= 2, Hydrogen = 8
MgBr2
Na2CO3
Magnesium = 1, Bromine = 2
Sodium = 2, Carbon = 1, Oxygen = 3
Mg(OH)2
C7H5(NO2)3
Magnesium = 1, Oxygen= 2, Hydrogen= 2
Carbon = 7, Hydrogen= 5, Nitrogen= 3,
Oxygen= 6
11. Use ball and stick illustrations to draw the following molecules.
Example: H2O =
a.) Ammonia (NH3)
b.) Baking Soda (NaHCO3)
Nitrogen = 1
Carbon=1, Sodium = 1,
Hydrogen = 3
Hydrogen= 1, Oxygen=3
12. Water’s chemical formula is H2O. The ratio of hydrogen atoms to oxygen
atoms is __2_:_1__.
13. A Compound is 2 or more different elements that are chemically bonded.
14. Which molecule best represents a compound?
a. Bromine Gas (Br2 )
b. Oxygen gas (O2)
c. Carbon Dioxide (CO2)
d. Aluminum (Al)
Conservation of Matter
15. How does the following chemical equation demonstrate that matter is
conserved?
The total mass of the Reactants is equal the total mass of the Products.
16. Label the equations as balanced or Unbalanced.
Chemical Reactions
Balanced or Unbalanced?
1
2Na + MgF2 → 2NaF + Mg
Balanced
2
H2 + O2 → 2H2O
Unbalanced
3
Mg + Cl2 → 2MgCl
Unbalanced
4
NaOH + 2HCl → NaCl + H2O
Unbalanced
17. In the above table, which equation shows the total mass during a chemical
reaction stays the same? _#1_______