Titration counts: One mole – can you imagine?
•
Since Avogadro and Loschmidt we call 6 . 1023 atoms or molecules one mole of a
substance. One mole = 602213673600000000000000 particles.
•
Can you imagine what that means?
- One mole of marbles spreaded on the globe would form a layer of 3 km thickness
- Assuming that a computer could count 10 Million molecules in one second, it would
need 2 trillions of years to count one mole of them
- One mole of dollar 100 Euro-bills stacked on top of each other would fill the distance
Sun-Pluto 7,5 million times
http://www.unit5.org/christjs/Stoichiometry/The%20Mole%20Concept.ppt#262,6,Careers in Chemistry – Philosopher
4.3.2. Titration-EN-1.0
CITIES Project N. 129193-CP-1-2006-1-DE–COMENIUS–C21
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Titration is what counts:
More images to represent one mole
•
Assuming that each human being has 60 trillion body cells (6.0 x 1013)
and the Earth's population is 6 billion (6 x 109), the total number of living
human body cells on the Earth at the present time is 3.6 x 1023or a little
over half of a mole.
•
If one mole of pennies were divided up among the Earth's population,
each person would receive 1 x 1014 pennies. Personal spending at the rate
of one million dollars a day would use up each persons wealth in about
three thousand years. Life would not be comfortable because the surface
of the Earth would be covered in copper coins to a depth of at least 400
meters.
http://lvstem.cse.lehigh.edu/teams/freedom/The%20Mole-intro-actvity-lesson%20plan.doc
•
Each screw in a package of screws and nuts corresponds to one nut – an
analogy for the reaction of monoprotic acid with e.g. NaOH-solution
4.3.2. Titration-EN-1.0
CITIES Project N. 129193-CP-1-2006-1-DE–COMENIUS–C21
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Titration is what counts
• When you weigh, you count molecules – 60 g of acetic acid
contain one mole of molecules
• When you now dilute or dissolve the acid, you have a defined
number of molecules in a given volume
• When you now titrate this solution to check the molarity, with e.g.
NaOH-solution, you react the number of acetic acid molecules
contained in the volume of solution with the base. If the hydroxide
ion content of the NaOH-solution is known, you can calculate the
concentration of the acid from the volume of base needed to
reach the equivalence point.
• Titration is a rapid, inexpensive and highly precise (and accurate)
method for the determination of analytes – and it does not need
calibration.
4.3.2. Titration-EN-1.0
CITIES Project N. 129193-CP-1-2006-1-DE–COMENIUS–C21
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Experiment:
• Titration of household vinegar to
measure the acetic acid content with
sodium hydroxide solution
• Phenolphthalein is used as an indicator
to mark the equivalence point
• The volume of hydroxide solution is
used to calculate the acid concentration
in the vinegar
http://www.dkimages.com/discover/previews/890/25053821.JPG
4.3.2. Titration-EN-1.0
CITIES Project N. 129193-CP-1-2006-1-DE–COMENIUS–C21
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The equivalence point of
the titration of vinegar
with NaOH lies in the
alkaline region, because
the resulting salt sodium
acetate is the salt of a
weak acid and a strong
base – hence it shows an
alkaline reaction (pink
colour of the solution
containing
phenolphtaleine as an
indicator)
“one nut for each screw“
phenolphthalein is
colourless in the acidic
and pink in the basic
region
4.3.2. Titration-EN-1.0
CITIES Project N. 129193-CP-1-2006-1-DE–COMENIUS–C21
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