Stoichiometry The quantitative study of chemical reactions

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: