Download balancing equations practice

Balancing Practice
Multiple Choice
Identify the choice that best completes the statement or answers the question.
____ 1. The principle underpinning the methods for balancing chemical reaction equations is:
a. conservation of mass
c. creation of atoms
b. conservation of charge
d. destruction of atoms
____ 2. What does a triangle on the right side of a chemical equation indicate
a. Heat is produced
c. Heat is absorbed in the reaction
b. Heat is necessary to start the
d. Potential energy associated with the
reaction
chemical bonds is increased
____ 3. An endothermic reaction feels
a. Hot
b. cold
c. can’t tell
d. rough and bumpy
____ 4. An exothermic reaction will feel
a. Hot
b. Cold
c. can’t tell
d. smooth
____ 5. What does the arrow in a chemical reaction equation mean?
a. it separates reactants from
c. stop
products, “yields”
b. “equals”
d. wrong way
____ 6. What does a double sided arrow in a chemical reaction equation mean?
a. The reaction is reversible
c. The reaction requires a catalyst
b. The reaction doesn’t happen
d. The reaction is spontaneous
____ 7. A chemical formula above the arrow indicates:
a. A catalyst that will speed up the
c. The reaction will not procede if the
reaction without being consumed
chemical is present
b. an element that appears out of thin d. The chemical is consumed in the
air
reaction
____ 8. How does a catalyst work?
a. By lowering the activation energy
b. By raising the activation energy
c. decreasing the temperature
d. absorbing excess heat
____ 9. What does a letter subscript in parenthesis after a reactant or product indicate?
a. The physical state of matter
c. the amount of reactant/product
b. the mass or volume of the
reactant/product
needed/produced
d. the intials of the guy who
discovered the reactant/product
____ 10. Coefficients indicate the number of formula units, or moles needed for a balanced reaction.
Where do they appear?
a. above and left of the element
c. Infront of, the same size and in line
symbol
with, the reactant/product
symbol/formula
b. below and right of the element
d. infront and below the formula
symbol
Matching
a. synthesis
b. single replacement
c. double replacement
d. decomposition
e. combustion
f. neutralizatoin
____ 11. AB + CD --> AD + CB
____ 12. A + B --> C
____ 13. A --> B + C
____ 14. A + BC --> AC + B
____ 15. CxHy + O2 --> CO2 + H2O
____ 16. HxB + A(OH)y --> AB + water
Short Answer
17.
Name the product and balance the reaction:
___Ta + ___O2 --> ___ ________ ?
Name of product________
18. Balance and identify the type of reaction: ____2NaI --> ____2Na + ____I2?
type ________
19. Balance and identify the type of reaction.
__FeS
+ __F2
--> __FeF2 + __S
type ________
20. Balance the reaction equation, and identify the ype of reaction.
___H2CrO4 +
___Os(OH)4 --Os(CrO4)2 + ___H2O
type ________
ec__________________________ name the salt produced above
Balancing Practice
Answer Section
MULTIPLE CHOICE
1. ANS: A
Just is...
PTS: 1
2. ANS: A
right side is products
Potential energy is stored in chemical bonds. If the reaction gives off heat (feels hot) then
the energy stored in the bonds is decreasing. The product bonds store less energy than the
reactant bonds.
PTS: 1
3. ANS: B
Endo thermic absorbs heat so it takes it from the surrounding, including the peson touching it,
so it feels cold.
PTS: 1
4. ANS: A
Exo meas gives off heat. It will feel warmer than it was before the reaction.
PTS: 1
5. ANS: A
Yields or products, makes, combine to form etc
PTS: 1
6. ANS: A
Goes both ways
PTS: 1
7. ANS: A
Catalyst that will speed up the reaction without being consumed.
PTS: 1
8. ANS: A
PTS: 1
9. ANS: A
(s)olid, (l)iquid, (g)as or (aq) aqueous (water) solution
PTS: 1
10. ANS: C
in front, same size
PTS: 1
MATCHING
11. ANS: C
PTS: 1
12. ANS: A
PTS: 1
13. ANS: D
PTS: 1
14. ANS: B
PTS: 1
15. ANS: E
PTS: 1
16. ANS: F
PTS: 1
SHORT ANSWER
17. ANS:
4Ta + 5O2 --> 2Ta2O5
Tantalum oxide
Tantalum;
oxide ;
180.948x2 = 361.896 (6 sigfig --> 3 decimal places)
15.9994x5 = 79.997 (6 sigfig --> 4 decimal places)
mass=441.8930000
sigfigs 441.893 (min of decimal places = 3)
PTS: 1
18. ANS:
2NaI --> 2Na + I2
Sodium iodide
Sodium;
22.98977x1 = 22.98977 (7 sigfig --> 5 decimal places)
iodide ;
126.905x1 = 126.905 (6 sigfig --> 3 decimal places)
mass=149.8947700
sigfigs 149.895 (min of decimal places = 3)
PTS: 1
19. ANS:
The products will be made by swaping the anions. Write the ions with charges swap charges
for subscripts and reduce by gcf.
FeF2 + Cs2S
greatest common factor of the balanced coefficients is 2
FeS
+ F2 --> FeF2 + S
Amass
87.907
12.85 grams
F2
Bmass
37.996806
Cmass
93.843806
32.06
Dmass
1 mole
1 mole S
32.06 grams S 10.842253
grams
37.996806
grams F2
1 mole F2
1 mole
PTS: 3
20. ANS:
The products will be made by swaping the anions. Write the ions with charges swap charges
for subscripts and reduce by gcf.
Osmium (IV) hydroxide and Hydrogen chromate
Os(CrO4)2 + H2O
greatest common factor of the balanced coefficients is 1
2H2CrO4
PTS: 3
+
Os(OH)4 --> Os(CrO4)2 + 4H2O