How many femur bones are in a single vault if an average vault wall measures 4m x 2m. Hint: 510femors/1m2.

1
Dimensional Analysis using Factor Label
How many femur bones are in a single vault if an
average vault wall measures 4m x 2m. Hint
510femors/1m2. How many people are buried in
an average size vault?
2
How many L of water travel over the Horseshoe
Falls in 1 year? How many L of water travel
over the Bridal Veil Falls in 3 years?
3
Mole
-An organism that lives in the ground and comes
out during the Spring to see its shadow!No!!
Just Kidding!! Thats a ground hog!! What is a
mole?1) 1mole 6.023x1023atoms, ions,
molecules 2) 1mole sum of atomic mass ex/N2
1mole (14.0067)2 28.0134g Na2SO4
1mole 22.9898(2) 32.064
15.9994(4) 142.0412g 3) 1mole 22.4L all
gases at STP
Invented since many times we need to do math
dealing with number of atoms, ions, molecules.
Scientists often dont like using large numbers
like 6.023x1023
Avagadros Number
Representative Particles
Formula Mass-ionic compounds Molecular
Mass-covalent compounds Molar Mass-both ionic
covalent
StandardTemp0CPressure1atm
4
Ex/ 1.2x1024 molecules H2 mole
H2? 2.6mole NaCl g NaCl? 38.0L
N2 mole N2?
5
Stoichiometry
-mathematical method used by chemists to predict
how much of a substance is needed or produced
from a chemical reaction-requires balanced
equation-involves moles of a substance to moles
another substance-uses factor label Ex/Debbie
adds 22.8g of Mg to a flask. How many L of H2
are produced? 3Mg 2H3PO4 ? Mg3(PO4)2
3H2 22.8g Mg 1mole Mg 3mole H2 22.4L H2
21.013L H2 24.305g Mg
3mole Mg 1mole H2
X mole ? y mole balanced equation
1mole ? 6.023x1023 atoms, ions, molecules1mole ?
? g1mole ? 22.4 L
6
Steps1)Balance Chemical Equation 2)Convert g,
L, atoms given ? moles given 3)Convert moles
given ? moles find 4)Convert moles find ? g, L,
atoms
7
ex/ Alex adds 2.5g of Na to a flask. How many
molecules of H2 are produced? Na H2O ?
NaOH H2 Ethan adds 3.0x1026 atoms of Fe to
a flask. How many L of O2 react? Fe O2
? Fe2O3 Sara pours 2.4L of Cl2 gas into a
beaker of water. How many g HCl is made? Cl2
2H2O ? HCl O2
8
Limiting Reactants -Substances not used up in a
reaction-Excess Reactant-Substance used up in a
reaction-Limiting Reactant-Limiting Reactant
stops the reaction once all consumed.-Used to
predict theoretical yield of a product. ex/ Mg
HCl ? H2 MgCl2 2.4g
3g ?g
9
Percent Composition -Used to determine amount of
each element in a compound.-Knowing percent
composition, can determine mass of each component
in a compound.-Common Application
Pharmaceutical Industry 1)determine
composition of an unknown compound 2)duplicate
compound to sell knowing the elements and
amounts of each in the compound
ex/Mg3(PO4)2 If you started with 150g
of Mg, how many g of P and O would you
need?