stoichiometry the quantitative study of chemical reactions
TRANSCRIPT
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 6.0 kg of H2 react with excess N2
to form NH3
Drill: Calculate the number of molecules
of oxygen gas required to burn
3.0 ng of C5H10O5
Chm II: Calculate the mass of Lead(II)iodide formed when 66.2 g of
lead (II)nitrate is combined with excess
potassium iodide
AP: Calculate the mass of solid product formed
when 66.2 g of lead (II)nitrate is combined with excess potassium
iodide solution
Chm II: Calculate the mass of MgCO3 formed when 18.4 g of MgBr2 is
combined with a solution containing
excess K2CO3.
Homework•Problem: 60
•Page 78
AP: Calculate the mass of solid product formed when 18.4 g of MgBr2 is
combined with a solution containing
excess K2CO3.
Chm II: Calculate the volume at STP of CO2 formed when 16.8 g of MgCO3 is decomposed creating CO2 & MgO.
AP: Calculate the volume at STP of gas
formed when 16.8 g of MgCO3 is decomposed
by heat.
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
Chm II: Calculate the mass of BaSO4 formed when 104 g of BaCl2 is combined with 250 mL
1.00 M K2SO4
AP: Calculate the mass of solid formed when
104 g of BaCl2 is combined with 250 mL
1.00 M K2SO4
AP Drill: Calculate the mass of solid formed
when 26.1 g of Ba(NO3)2 is combined
with 25 mL 1.00 M K2SO4
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.
Drill: 510 g PH3 was obtained when 0.62 kg of P4 reacts with
excess H2. Calculate percent yield.
Review HW•Problem 31
•on page 115
Determine the mass of PH3 formed at STP
when 2.0 x 1027 molecules P4 reacts with
4.0 kg of H2:
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 solid product formed when 41.6
g of barium chloride is added to 250 ml of 0.40 M potassium sulfate giving a
50.0 % yield:
Calculate the mass of solid product formed
when 2.00 g of calcium bromide is added to 250 ml of
0.40 M sodium sulfate:
4.61 g of lead(II)iodide was obtained when 66.2 g of
lead(II)nitrate was added to 750 ml 0.10 M potassium
iodide. Calculate the % yield & the molarity of all ions remaining in the solution.
33.1 g of lead(II)nitrate was added to 1500 mL
0.10 M potassium iodide. Calculate mass
of solid product 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 volume of oxygen
gas at STP required to burn 240 mg
C5H8O2: