Stoichiometry
From the Greek words
“stoicheion” meaning “element”
and “metron” meaning “measure”
Stoichiometry
• Involves the mass relationships between
reactants and products in a chemical
reaction.
• All reaction stoichiometry relationships start
with a balanced chemical equation.
• Equation gives the relative numbers of
moles of reactants and products.
• Solve problems using RATIOS from the
balanced equation.
Subscripts and Moles
Coefficients and Moles
What is a mole ratio?
❖A mole ratio is a ratio between the number of moles of any two
substances in a balanced chemical equation.
❖Mole ratios are written as ratios or fractions.
C2H5OH + 3O2 → 2CO2 + 3H2O
Examples:
1 mol C2H5OH: 2 mol CO2 or
3 mol O2: 2 mol CO2 or
Mole Ratio
Ratios produced from
the balanced equation
2H2 + O2 2H2O
• Possible mole ratios:
1O2 2H2O
• 2H2 2H2
1O2 1O2 2H2O
2H2O 2H2 2H2O 2H2
1O2
Warm Up
2 C4H10 + 13 O2 → 8 CO2 + 10 H2O
Give all the possible mole ratio for the
given equation above.
Warm Up
C4H10 + O2 → CO2 + H2O
Give all the possible mole ratio for the
given the equation above.
12 possible mole ratio
Lecture Notebook: Construct the mole
ratio for each balanced reaction.
SnO2 + 2H2 → Sn + 2H2O
Cu + 2AgNO3 → Cu(NO3)2 + 2Ag
3Pb(NO3)2 + 2AlCl3 → 3PbCl2 + 2Al(NO3)3
Assignment:
2Ca3(PO4)2 + 6 SiO2 + 10C
6 CaSiO3 + P4 +10CO
Give all the possible mole ratio for the
given balanced equation above.
Calculations that Involve
Balanced Chemical Reactions
• Mole to Mole Conversion
• Mole to Mass Conversion
• Mass to Mass Conversion
Calculations that Involve Balanced Chemical Reactions
1. Mole-to-Mole Conversion
If the number of moles of one substance is
given in the problem, we can
determine the number of moles of any of the
other substances in the chemical
reaction or chemical equation by using a
mole conversion factor based on the
coefficients in the balanced chemical
equation.
Calculations that Involve Balanced Chemical Reactions
1. Mole to Mole Conversions
given/unknown = mole/mole
Amount of given Amount of unknown
Substance (mol) substance (mol)
Lecture Notebook:
Mole to Mole Conversions Examples
Activity NB
Mole to Mole Conversions Examples
Calculations that Involve Balanced Chemical Reactions
2. Mole-to-Mass Conversion
The gram is the most convenient unit
for measuring amounts of reactants or
products in the laboratory. To convert
moles to grams or grams to moles,
you must make use of the molar mass
of the given compound.
Calculations that Involve Balanced Chemical Reactions
2. Mole to Mass Conversion
given/unknown = mole/mass(g)
Amount of given Amount of unknown
Substance (mol) substance (grams)
Lecture Notebook:
Mole to Mass Conversion Examples
Activity NB
CaCO3+ 2HCl→CaCl2+CO2+H2O
How many grams of CO2 are
produced if 2.09 mol of HCl
reacts with CaCO3?
Mole to Mass Conversions Examples
Calculations that Involve Balanced Chemical Reactions
3. Mass-to-Mass
Conversion
If the problem asks for the
mass in grams of one
substance and the mass of
another substance is given.
Calculations that Involve Balanced Chemical Reactions
3. Mass to Mass Conversions
given/unknown = mass(g)/mass(g)
Amount of given Amount of unknown
Substance (grams) substance (grams)
How many grams of O2 are needed to react with
250 g of C2H6?
Lecture Notebook:
Mass to Mass Conversion Examples
Activity NB
CH4(g)+Cl2(g)→ CCl2(l)+ HCl(l)
How many grams of HCl
are produced by the reaction of 100.0 g
of CH4?
Mass to Mass Conversions Examples
I would really
appreciate it if
you study for the
quiz class
tomorrow. Thank
you
Quiz
Mole to Mole Conversions Examples
Quiz
Fe2O3+ SO3→Fe2(SO4)3
If we have 3.59 mol of Fe2O3,
how many grams of SO3 can
react with it?
Mole to Mass Conversions Examples
Quiz
NH4NO3(s)→N2O(g)
+2H
Ammonium nitrate 2O(l) to dinitrogen
decomposes
monoxide and water according to the
following equation. In a certain experiment,
45.7g of ammonium nitrate is decomposed.
Find the mass of each of the products
formed.
Mass to Mass Conversions Examples
