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Culver City H.S.  AP Chemistry
2  Atoms, Molecules, and Ions
Station 1 – NAMING COMPOUNDS & WRITING FORMULAS
Write the formulas for the following compounds:
Name
Formula
Name the following compounds:
Formula
Name
Dinitrogen pentoxide
BF3
Aluminum oxide
SF6
Tin (IV) sulfate
(NH4)2Cr2O7
Oxygen difluoride
PbCO3
Carbon tetrachloride
NI3
Culver City H.S.  AP Chemistry
3  Stoichiometry
Station 2 –AVERAGE ATOMIC MASS
The element rhenium (Re) has two naturally occurring isotopes, 185Re and 187Re, with an average atomic mass
of 186.207 amu. Rhenium is 62.60% 187Re, and the atomic mass of 187Re is 186.956 amu. Find the mass of
185
Re.
Culver City H.S.  AP Chemistry
3  Stoichiometry
Station 3 – % COMPOSITION
Use your periodic table and calculator to determine the % composition (by mass) of each element in:
Note: Give your answers to 1 decimal place.
Formula
%Ca
%C
%N
Ca(CN)2
Calculation Area:
Culver City H.S.  AP Chemistry
3  Stoichiometry
Station 4 – EMPIRICAL FORMULAS
Determine the molecular formula given the following information:
Empirical Formula
Molecular Formula
Molar Mass
CH2
84.18 g·mol-1
NO2
92.02 g·mol-1
NaSO2
174.14 g·mol-1
PCl3
137.32 g·mol-1
Culver City H.S.  AP Chemistry
3  Stoichiometry
Solve the following general stoichiometry problems:
Station 5 – STOICHIOMETRY
(Show work beautifully.)
N2(g) + 3H2(g)  2NH3(g)
[Molar Masses: 28.02 g·mol-1
2.02 g·mol-1
17.04 g·mol-1]
Calculate the mass of ammonia, NH3, formed when 45.0 L N2(g) reacts with excess H2(g) at STP.
What mass of H2 is needed to completely react with 10.0 grams of N2?
Culver City H.S.  AP Chemistry
3  Stoichiometry
Station 6 – LIMITING REACTANT PROBLEMS
Solve the following problem:
N2(g) + 3H2(g)  2NH3(g)
[Molar Masses: 28.02 g·mol-1
2.02 g·mol-1
17.04 g·mol-1]
What mass of NH3 is formed when 135.00 g N2 reacts with 32.00 g H2?
Culver City H.S.  AP Chemistry
3  Stoichiometry
Station 7 – PERCENT YIELD
Solve the following problem:
Hydrogen gas was generated according to the equation: Zn(s) + 2HCl(aq)  H2(g) + ZnCl2(aq)
When 25.00 grams of Zn metal reacted with excess HCl 7.50 L H2(g) was collected at STP.
The theoretical yield of H2(g) for this reaction is: (show work)
The percentage yield for this reaction is: (show set-up)
Culver City H.S.  AP Chemistry
3  Stoichiometry
Station 8 – EMPIRICAL FORMULA FROM % COMPOSITION
Determine the empirical formula of the compound from the following %composition (by mass) information:
A compound composed of carbon and hydrogen is found to contain 85.6% C and 14.4% hydrogen by mass.
What is the empirical formula of the compound? ____________
Calculation Area:
Culver City H.S.  AP Chemistry
3  Stoichiometry
Station 9 – CHEMICAL ANALYSIS
Solve the following problem:
A compound composed of carbon and hydrogen is analyzed by combustion.
When a 4.297 g sample of the compound is burned, 12.57 g CO2 and 7.72 g H2O are formed.
What is the empirical formula of the compound? ________________
The molar mass of the compound is found to be about 30 g·mol-1.
The molecular formula for the compound is _________________
Culver City H.S.  AP Chemistry
3  Stoichiometry
Station 10 – HYDRATES
A student is assigned the task of determining the number of moles of water in one mole of MgCl2 · n H2O.
The student collects the data shown in the following table.
Mass of empty container
Initial mass of sample and container
Mass of sample and container after first heating
Mass of sample and container after second heating
Mass of sample and container after third heating
Determine the moles of water lost when the sample was heated.
Determine the formula of the hydrated compound.
22.347 g
25.825 g
23.982 g
23.976 g
23.977 g