Download 10-Stoichiometry

Stoichiometry
•The quantitative
study of chemical
reactions
Stoichiometric Steps
• Set up & balance rxn
• Change stuff given to moles
• Change moles given to ask
• Change what’s asked for to
the proper unit
Step 1
•Determine products of
a reaction if they are
not given
•Balance the reaction
Step 2
•Use molar conversion
to change whatever is
given to moles
Step 3
•Use the molar ratio from
the balanced reaction to
convert the moles of what
is given to the moles of
what’s asked for.
Step 4
•Use molar conversions
to change the moles of
what is asked for to
the proper unit
Calculate the volume
of NH3 formed at STP
when 6.00 kg of H2
react with excess N2
to form NH3
Calculate the volume
of NH3 formed at STP
when 6.00 kg of H2
react with excess N2
to form NH3
Calculate the mass of
PbI2 formed when
66.2 g of Pb(NO3)2 is
combined with excess
KI.
Calculate the number
of molecules of
oxygen gas required to
burn 3.5 ng of C5H10
Calculate the mass of
MgCO3 formed when
18.4 g of MgBr2 is
combined with a
solution containing
excess K2CO3.
Calculate the volume of
CO2 formed at STP
when 16.8 g of MgCO3
is decomposed creating
CO2 & MgO.
Limiting Reactant
•The reactant that gets
used up
•The reactant that
determines the amount of
product formed
Excess Reactant
•The reactant that
does not get used
up
Stoichiometry with
Multiple Reagents
•Perform same steps for
all reactants
•Choose least amount of
product
Calculate the mass of
glucose (C6H12O6)
formed when 880 g of
carbon dioxide is
combined with 720 g of
water in photosynthesis
Calculate the # of
molecules of NH3
formed when
4.0 mg of H2 react with
1.12 mL of N2 gas at
STP.
Theoretical Yield
• The amount determined
through stoichiometry
• The amount solved for
on paper
Experimental Yield
•The amount obtained
in the lab
•Actual yield
Percent yield
% Yield =
(Exp/Theo) x 100 %
68 g NH3 was
obtained in lab when
140 g of N2 reacts
with excess H2.
Calculate percent
yield.
510 g PH3 were
obtained in the lab when
0.62 kg of P4 reacted
with excess H2.
Calculate percent yield.
Determine the volume
of O2 released at STP
when 32 kg of Fe2O3
is purified with an
80.0 % yield making
Fe & O2
Calculate the volume
of oxygen gas at STP
required to burn 12 kg
of erythrose (C4H8O4)
Calculate the mass of
BaSO4 formed when
41.6 g of BaCl2 is
added to 17.4 g K2SO4
giving a 50.0 % yield:
Calculate the mass of
CaSO4 formed when
2.00 g of calcium
bromide is added to
75 mL of 0.40 M
sodium sulfate:
Terms:
Stoichiometry Percent yield
Limiting Reactant
Excess reactant
Theoretical yield
Experimental yield
Calculate the
volume in mL of
oxygen gas at STP
required to burn
50.0 mg C5H8O2:
3.67 g of PbBr2 was
obtained in lab when
6.62 g of Pb(NO3)2 was
added to 11.9 g KBr.
Calculate the % yield.
Calculate the volume of
gaseous product formed
when 4.2 kg of MgCO3
is heated with a 75 %
yield:
MgCO3  MgO + CO2
Calculate the volume of
Cl2 collected at STP
when 3.80 mg of F2 at
STP is bubbled through a
0.050 mL solution of
0.020 M KCl:
Calculate the volume
in mL of gaseous
products formed at
STP when 6.0 mg of
C2H6 is burned in
excess oxygen:
33.1 g of Pb(NO3)2
was added to 1500
mL 0.10 M KI.
Calculate mass of
PbI2 formed.
Chm II: Calculate the mass
of water & NaCl formed
when 6.0 g of sodium
hydroxide is added to a
250 mL solution 0.40 M
hydrochloric acid:
Chm II: 33.1 g of
Pb(NO3)2 was added
to 1500 mL 0.10 M
KI. Calculate mass of
PbI2 formed.
Chm II: 29.7 g of
BaBr2 was added to
1500 mL 0.10 M
K2SO4. Calculate
mass of BaSO4
formed.
An 30.0 g unknown sample
(containing only C, H, &
O) was burned in excess
oxygen yielding 66 g CO2
& 36 g H2O. Calculate its
empirical formula :
An 240 g unknown sample
(containing only C, H, S, &
O) was burned in excess
oxygen yielding 352 g CO2,
144 g H2O, & 128 g, SO2.
Calculate its empirical
formula :
Calculate the mass of
solid product formed
when 3.31 g of Pb(NO3)2
is added to a 75.0 mL
solution 0.20 M KI:
Name the Following:
BaCl2
Mn2O3
SF2
NH3
CaSO4
(NH4)3PO3
Fe(NO3)2 KClO3
Derive formulas for
Sodium hydroxide
Calcium carbonate
Iron(III)phosphate
Dinitrogen tetroxide
Make conversions:
•64 kg SO2 to mL gas
•11.2 mL NH3 to atoms
•180 km/hr to cm/s