The Mole
1 dozen eggs = 12 eggs
1 Gross pencils = 144 pencils
1 Ream of paper = 500 sheets of paper
The Mole
• 1 mole = 6.022 x 1023 things
– Avogadro’s number
• The number of carbon atoms in 12g of C-12
• Abbreviation: “mol”
How much does this weigh?
• 1 mole C atoms = 6.022 x 1023 Carbon atoms
• 6.022 x 1023 Carbon atoms = 1 mole of carbon
atoms
• 1 mole bicycles = 6.022 x 1023 bicycles
• 6.022 x 1023 bicycles = 1 mole of bicycles
• 1 mole of anything = 6.022 x 1023 items of anything
• 6.022 x 1023 items of anything = 1 mole of anything
Cu, Al, Pb, S, Mg, Cr
Molar Mass
• The mass, in grams, of one mole of any
element or compound
• Abbreviated with capital, italicized M
• Unit = grams/mole = g/mol
• Also called Formula Mass and Formula Weight
Problems
1) You need 0.250 mol Cu for an
experiment, how many grams should you
use? How many atoms of Cu is this?
2) You have 145.9 g Hg. How many moles
are present? If Hg has a density of 13.53
g/mL, what volume do you have?
ClNa+
Na+
3) Write the molecular
formula or formula unit
for the compounds
above.
4) What are the
molecular and formula
weights for the
compounds above?
5) What is the mass of
1.34 mole of the first
compound? What is
the mass of carbon in
this sample?
Cl-
Cl-
ClNa+
Na+
6) How many moles of
Sodium Chloride are
present in 9.29 g?
How many moles of
sodium are present in
the sample?
7) How many oxygen
atoms are there in
5.62g of Carbon
Dioxide?
10)Your nurse gives you 10.0g morphine,
C17H19NO3 , for pain. How many moles is
this? How many grams of oxygen are
present in this dose of analgesic?
Chemical Equations
Coefficient
Physical State
Subscript
H2 (g) + Cl2(g)  2 HCl (g)
Reactants
Product(s)
Law of Conservation of
Matter/Mass
• Matter is neither created, nor destroyed,
but is merely rearranged
• The mass of the reactants must equal
the mass of the products
• H2 (g) + Cl2(g)  2 HCl (g)
Balancing Chemical Equations
Zn(s) + HCl(aq)  H2(g) + ZnCl2(aq)
1)
2)
3)
4)
Write the unbalanced equation
Balance the atoms of one element
Choose another element and balance it
Continue until all elements have the same
number of atoms on both sides of the
equation
5) Check yourself
Problems
1)
2)
3)
4)
__ N2(g) + __ H2(g)  __ NH3(g)
__ Fe(s) + __ Cl2(g)  __ FeCl3(s)
__NH3(g) + __O2(g)  __NO(g) + __H2O(g)
__C5H12(l) + __O2(g)  __CO2(g) + __H2O(g)
General Reactions
• Combination rxns: 2 or more substances
react to form a single product
• 2 H2 + O2  2 H2O
• Decomposition rxns: single substance
decomposes into 2 or more products
• opposite of combination rxns
• 2 H2O  2 H2 + O2
• Single replacement/displacement: one
element reacts with a compound to form
a new compound and release a new
element
• 2 Na + 2 H2O  2 NaOH + H2
• Exchange or Double replacement/displacement:
an interchange of partners between two compounds
• Pb(NO3)2(aq) + K2CrO4(aq)  PbCrO4(s) + 2 KNO3(aq)
• Combustion rxns: the burning of a
compound, usually a hydrocarbon, in
oxygen to form heat, carbon dioxide and
water
Problems
Balance the following equations and identify the type of
reaction present.
1)__C3H8(g) + __O2(g)  __CO2(g) + __H2O(g)
2)__BaCl2(aq) + __Na2SO4(aq)  __BaSO4(s) + __NaCl(aq)
3)__Fe(s) + __H2O(l)  __Fe3O4(s) + __H2(g)
4)__Pt(s) + __F2(g)  __PtF4(l)
5)__H3BO3(s)  __B2O3(s) + __H2O(l)
6)__C4H10(g) + __O2(g)  __CO2(g) + __H2O(g)
Stoichiometry Problems
1) If you have 10.0g C4H10 (butane), how
many grams of water can you make
upon combustion?
2) How much O2 do you need in problem 1
if you’d like to produce 7.39g CO2?
3) How much CO2 is produced upon
combustion of 4.3g of propane (C3H8)?
4) Using the equation below, calculate
the amount of glucose you started with
if you produced 12.76g CO2?
5) How much glucose was consumed in
order to produce 100.0 mL of H2O?
__C6H12O6(s) + __O2(g)  __CO2(g) + __H2O(l)
Jim Bob got a job at a chair factory. His
boss tells him that he’s going to lunch
and when he comes back, Jim Bob better
have 5 chairs made or he’s fired. JB gets
to work. He counts 32 arms, 18 legs, 4
backs, and 2 seats. Will JB get fired?
Limiting Reagent
• Limiting
Reagent/Reactant/Fact
or: the reactant/factor
that determines the
amount of product
formed
• Other reactants are “in
excess”
• Cheaper reactants are
usually in excess
Problems
1) You have 10.0 moles H2 and 1.00 mol
O2. How much H2O can you make?
2) You combust 10.2 mol propane in 7.80
mol O2. How much CO2 can you
produce?
3) If 2.3 mol carbon disulfide reacts with
5.4 mol oxygen to form carbon dioxide
and sulfur dioxide, what mass of sulfur
dioxide is formed?
4) 5.50 g silicon dioxide reacts with 4.71g
Carbon to from silicon carbide and
carbon monoxide. What mass of
carbon monoxide is formed?
Percent Yield
• Theoretical Yield: the maximum possible
quantity of product
• 100% yield
• Actual/Experimental Yield: quantity of
product actually obtained
• Percent Yield: efficiency of reaction
• PY = (actual yield/theoretical yield) x 100
Problems
1) From the previous question, the
theoretical yield of CO is 5.13 g. If you
obtained 4.32g CO, what was your %
yield?
2) You react 4.41 mol carbon monoxide
with 8.39 mol hydrogen gas to get 122g
methanol. What is your percent yield?