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Exam Review - Chapter 2: Stoichiometry
1) The formula for fructose is C6H12O6. Which
of the following is true for fructose?
____ a) the empirical formula is C2H4O2
____ b) there is a total of six atoms in each
molecule
____ c) a molecule contains six carbon atoms
____ d) the ratio of carbon to oxygen atoms is
1:2
2) A positively charged ion
____ a) is formed when an atom loses electrons
____ b) is called an anion
____ c) is formed when an atom gains a proton
____ d) has more electrons than protons
3) Which of these ions has the same electron
configuration as Ar?
____ a) Na+1
____ b) Ca+1
____ c) S-1
____ d) Cl-1
4) Monatomic anions (negative ions) are
named with the suffix
____ a) -ide
____ b) -ate
____ c) -ite
____ d) -ade
5) To use the criss-cross method of writing the
formula of an ionic compound, write the
numerical charge of
____ a) the cation as the subscript of the cation
____ b) the anion as the subscript of the cation
____ c) each ion as its own subscript
____ d) each ion as its own superscript
6) What is the name for the compound
(NH4)3PO4?
____ a) triammonium quatrophosphate
____ b) polyammonum phosphate
____ c) ammonium phosphate
____ d) ammonium (III) phosphate
7) What is the name of the compound whose
formula is FeSO4?
____ a) iron (II) sulfate
____ b) iron sulfate
____ c) iron (III) sulfate
____ d) iron (I) sulfate
8) Determine the formula of the compound
formed between calcium and hydroxide ions.
____ a) CaOH
____ b) Ca(OH)2
____ c) CaOH2
____ d) Ca2OH
9) Determine the formula of the compound
aluminum phosphide.
____ a) AlP
____ b) AlPO4
____ c) Al(PO)4
____ d) Al3(PO4)3
10) Determine the formula for copper (II)
chloride.
____ a) Cu2Cl
____ b) (CuCl)2
____ c) CuCl
____ d) CuCl2
11) Determine the formula for iron (III) nitrate.
____ a) Fe(NO3)3
____ b) FeN
____ c) Fe3NO3
____ d) Fe3(NO3)3
12) A substance that enters into a chemical
reaction is called a
____ a) mole
____ b) product
____ c) coefficient
____ d) reactant
13) The word equation “magnesium reacts
with chlorine to produce magnesium chloride
would be represented by which of the following
formula equations?
____ a) Mg + Cl ---> MgCl
____ b) Mg + 2 Cl ---> MgCl2
____ c) Mg + Cl2 ---> MgCl2
____ d) MgCl ---> Mg + Cl
14) In a chemical reaction, what is the
relationship between the total mass of the
reactants and the total mass of the products?
____ a) they must be equal
____ b) the mass of the products must be
greater
____ c) the mass of the reactants must be
greater
____ d) there is no general relationship
between the two
15) In balancing a chemical equation, which of
the following are you allowed to do?
____ a) change subscripts
____ b) write coefficients
____ c) change charges
____ d) add new substances
H. Chem
16) Which of the following means a substance
dissolved in water?
____ a) (aq)
____ b) (s)
____ c) (w)
____ d) (l)
17) What number should be written in front of
Na to balance the equation
___ Na + ___ MgCl2 ---> ___ NaCl + ___ Mg
____ a) 1
____ b) 2
____ c) 3
____ d) 4
18) In what kind of reaction does an
uncombined element displace an element that
is part of a compound?
____ a) synthesis
____ b) double replacement
____ c) single replacement
____ d) decomposition
19) What kind of reaction is represented by the
equation
CH4 + 2 O2 ---> CO2 + 2 H2O
____ a) synthesis
____ b) single replacement
____ c) double replacement
____ d) combustion
20) Balance the chemical equation Al + F2 --->
AlF3
____ a) already balanced
____ b) 2 Al + F2 ---> 2 AlF3
____ c) Al3 + F6 ---> Al3F6
____ d) 2 Al + 3 F2 ---> 2 AlF3
21) Mercury (II) oxide, HgO, is heated until it is
broken down into its elements. Which is a
balanced equation for the reaction?
____ a) HgO2 ---> Hg + O2
____ b) 2 HgO ---> 2 Hg + O2
____ c) 2 HgO ---> 2 Hg + 2 O
____ d) HgO ---> Hg + O
22) Write a balanced equation for a reaction in
which gaseous ethane (C2H6) burns in air.
____ a) C2H6 (g) ---> C2 (g) + 3 H2 (l)
____ b) C2H6 (g) + O2 (g) --->
2 CO2 (g) + 3 H2O (l)
____ c) 2 C2H6 (g) + 7 N2 (g) --->
4 CN2 (g) + 6 H2N (l)
____ d) 2 C2H6 (g) + 7 O2 (g) --->
4 CO2 (g) + 6 H2O (l)
23) When an element and a compound
undergo a chemical reaction, the type of
reaction is called a
____ a) single replacement
____ b) double replacement
____ c) synthesis
____ d) decomposition
24) When two substances come together to
make one compound, this is called a _________
reaction.
____ a) combustion
____ b) synthesis
____ c) decomposition
____ d) single replacement
25) What is the molar mass of Zn(NO3)2?
____ a) 159 g/mol
____ b) 189 g/mol
____ c) 173 g/mol
____ d) 255 g/mol
26) How many atoms are in a sample of an
element whose mass in grams is numerically
equal to the atomic mass?
____ a) 1
____ b) 6.02 x 1023
____ c) 1 x1023
____ d) 6.02
27) Which of the following normally exists as a
diatomic element?
____ a) sodium
____ b) chlorine
____ c) neon
____ d) sulfur
28) What is the empirical formula of a
compound whose molecular formula is C2Cl6?
____ a) CCl3
____ b) CCl4
____ c) CCl
____ d) C2Cl6
29) What is the molecular formula for a
compound whose empirical formula is CH and
has a molar mass of 39 g/mol?
____ a) CH
____ b) C2H2
____ c) C3H3
____ d) C4H4
30) In a balanced equation describing a
chemical reaction involving solid substances,
the coefficients refer to the relative number of
____ a) grams
____ b) liters
____ c) cubic centimeters
____ d) particles
H. Chem
31) The number of mole of a reactant or
product is determined by dividing its mass by
____ a) Avogadro’s number
____ b) the molar mass of the substance
____ c) the volume of the substance
____ d) the molar ration of reactants to
products
32) In mass-mass problems, the steps to follow
are best summarized as going from
____ a) grams to moles to moles to grams
____ b) liters to moles to liters to moles
____ c) grams to moles to moles to liters
____ d) grams to moles to liters to molecules
33) Which type of stoichiometry problem is
essential to solving the other types?
____ a) mass-mass
____ b) mass-volume
____ c) volume-particles
____ d) mole-mole
34) When two reactants are available in
stoichiometric proportions represented by the
chemical reaction
____ a) only the most massive reactant will be
used up
____ b) neither of the reactants will be used up
____ c) both of the reactants will be used up
____ d) only the least massive reactant will be
used up
35) The limiting reactant in a completed
chemical reaction will be the substance
____ a) used up
____ b) left over
____ c) with the greatest mass before the
reaction
____ d) with the least mass before the reaction
Use the following diagram to answer questions
37 & 38.
37) The reaction of methane and oxygen is
represented by the equation
CH4 + 2 O2 ---> CO2 + 2 H2O. If the balloons of
methane and oxygen in the figure above are
forced into a third container and allowed to
react, what substances will be present in the
container after the reaction is over?
____ a) carbon dioxide and water
____ b) carbon dioxide, methane, oxygen and
water
____ c) carbon dioxide, water and oxygen
____ d) carbon dioxide, water and methane
38) The reaction of hydrogen and chlorine is
represented by the equation
H2 + Cl2 ---> 2 HCl. If the balloons of hydrogen
and chlorine in the figure above are forced into
a third container and allowed to react, what
substances will be present in the container
after the reaction is over?
____ a) hydrogen chloride
____ b) hydrogen chloride and chlorine
____ c) hydrogen chloride and hydrogen
____ d) hydrogen chloride, hydrogen and
chlorine
36) The percent yield of products from a
chemical reaction is the ratio of
____ a) expected yield to actual yield
____ b) actual yield to expected yield
____ c) actual yield to minimum yield
____ d) expected yield to minimum yield
H. Chem
Problems:
1) Calculate the volume of a balloon filled with 15.0 g of NO2 at STP.
2) Calculate the number of moles of 76.1 g SO2.
3) An 11.78 g sample of an unknown compound is decomposed and analyzed. The procedure
produces 0.36 g of H, 3.73 g of P and 7.69 g of O. Determine the percent composition of hydrogen in
the compound.
4) What is the percent of oxygen by mass in water?
5) A sample of ammonia (NH3) contains 7.22 moles of ammonia. How many molecules of ammonia
are in the sample?
6) What is the mass of 2.0 mol of CuCl2?
7) A susbstance is analyzed and determined to be made up of 69.4 % carbon, 4.13 % hydrogen, and
26.4 % oxygen. The molar mass of the substance is found to be 242 g/mol.
a) What is the empirical formula for the substance?
b) What is the molecular formula for the substance?
8) How many liters of ammonia gas would be produced by 3.00 grams of magnesium nitride,
according to the reaction Mg3N2 + 6 H2O --> 3 Mg(OH)2 + 2 NH3?
9) Solid iron (II) sulfide reacts with aqueous hydrochloric acid (HCl) to produce hydrogen sulfide gas
and a solution of iron (II) chloride. How many grams of hydrochloric acid must react to produce 2.50
L of hydrogen sulfide at STP?
10a) When CH4 burns in the presence of oxygen, it produces CO2 and H2O. What mass of water
would be made from 4.25 g of CH4?
b) If 9.05 g of water is recovered when performing the lab, what is the percent yield of the lab?
11) Copper is made by mixing aqueous copper (II) chloride with solid aluminum. If a solution
containing 32.4 g of copper (II) chloride is mixed with 5.00 g of aluminum powder, how many grams
of copper would be produced?
Answers to problems
1) 7.30 L
2) 1.19 mol
5) 4.35 x 1024 molecules
8) 1.34 L
9) 8.15 g
3) 3.1 % H
6) 269 g
10a) 9.56 g
4) 88.9 % O
7) C7H5O2, C14H10O4
b) 94.7 %
11) 15.3 g
H. Chem