Special Topics Math and chemistry review, solutions, and concentrations .
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Transcript of Special Topics Math and chemistry review, solutions, and concentrations .
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Special TopicsMath and chemistry review,
solutions, and concentrations
http://www.youtube.com/watch?v=lMW5YYiEfgU
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Outline
I. Metric system reviewII. Concentration of solutions
A. SoluteB. SolventC. Grams %D. Molarity (M)E. Molality (m)F. Osmolality and dissolutionG. Sample problems
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Symbol prefix 100 1 one
d deci* 101 0.1 tenth
c centi* 102 0.01 hundredth
m milli 103 0.001 thousandth
µ micro 106 0.000 001 millionth
n nano 109 0.000 000 001 billionth
p pico 1012 0.000 000 000 001 trillionth
f femto 1015 0.000 000 000 000 001
a atto 1018 0.000 000 000 000 000 001
z zepto 1021 0.000 000 000 000 000 000 001
y yocto 1024 0.000 000 000 000 000 000 000 001
http://micro.magnet.fsu.edu/primer/java/scienceopticsu/powersof10/index.html
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King Henry Slider
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Distance, volume, mass and temperature
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Scientific Notation
• The notation is based on powers of base number 10. The general format looks something like this:
• N X 10x • where N= number greater than 1
but less than 10 and x=exponent. • Placing numbers in exponential
notation has several advantages. • Concise! • Easier math without your
calculator!• Let’s practice!
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Now let’s talk about solutions Water is the most abundant liquid on the
earth and is necessary for all life. Because of water's great dissolving properties, any sample is a solution
containing solids, other liquids, and gases from the environment.
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Aqueous solutions
• A solution is a homogeneous mixture of ions or molecules of two or more substances.
• Two parts• Solvent is the component
that is in the largest quantity (water)
• Solute is the component that is dissolved in the solvent.
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Concentration
• A measure of how much of a substance (solute) is dissolved in another substance (solvent)
• To calculate [concentration]:
• Common usages of concentration:• Mass (m/v) conc. (grams%= grams per 100 ml, etc.)• Molarity (units are moles/L or M)• Molality (units are moles/kg or m)• osmolality
solventofamount
soluteofamountsoluteofconc .
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gm %
• Let’s practice:• What is the gm% of 5.0 x101 g
of NaCl in 100 ml of water?• What about 0.009 gm in 100ml
of water?• Of the three ways we will
determine a solution’s concentration, this is the easiest one.
• Why?
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In the case of dilute aqueous solutions, scientists often use the approximationapproximation:
We are walking sacks of dilute aqueous solutions.
Molarity (mol/L) = Molality (mole/kg solvent)This is a very close approximation for dilute solutions
because:
• 1) 1 kg of water 1 L
• 2) volume of solvent >> volume of solute therefore:– volume of solution volume of solvent– mass of solution mass of solvent
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Molality (moles/kg)• What is a mole?• Avogadro’s number: 6.02 x 10 23
• Number of atoms or molecules necessary to reach atomic or molecular mass in grams
• How much does one mole of sodium weigh?
• Sodium Chloride?• Need periodic table
Above I show some pictures: one is a poor representation of a great Italian theoretician: the other a good representation of a poorly spelled Italian theoretician. I implore my students to notice the differences.
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Dissociation factor to determine osmolality (dissolution)
• Ionic compounds that are soluble in water dissociate completely and exist in solution entirely as ions.
• Soluble ionic compounds are strong electrolytes.
• NaCl, KCl, MgCl2, HCl, CaCl2
• Molecular compounds such as sugars, proteins, fats and alcohol are non-electrolytes. They have no tendency to come apart, and they exist in solution entirely as aqueous molecules.
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• What is the osmolality of a
5.4 % glucose solution?
• Is the solution hyperosmotic, hypo-osmotic, or isosmotic?
Question
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Steps to complete the task• Write out the grams%• Convert to grams per liter (multiply by
1000ml/ 1 Liter)• Convert the grams to moles (you need
MW to do this! Multiply by 1mole/mw gms of substance)
• multiply by 1,000mmole/Mole to get mmole
• You now have mM/L . Multiply by 1L/1kg to convert to molality (mM/kg)
• Multiply by the dissociation factor and you now have osmolality! (glucose and proteins are “1”)
• The chorus breaks out into song!
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Osmolality of a 5.4 % Glucose Solution
MW glucose = 180 gm/mol5.4 % = 5.4 gm 100ml5.4gm X 1000ml = 54 gm 100ml L L
Isosmotic—what would the cell do?
54 gm x 1 mol = .3 mol X 1000mmol =L 180 gm L 1 mole
Dissociation factor is one so: 300 mOsmkg
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• What is the osmolality of a 3.0% NaCl solution?
Question
• Is the solution hyperosmotic, hypo-osmotic, or isosmotic?
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Osmolality of a 3% NaCl Solution
For NaCl, 1 mmol = 2 mOsm513 mmol x 2 mOsm = 1026 mOsm = 1026mOsm/kg
LL mmolHyperosmotic—what would the cell do?In order to understand this concept, you need to learn about body fluid compartments!
MW NaCl = 58.53 % = 3 gm/100ml 3 gm X 1000ml = 30 gm 100ml L L
30 gm x 1 mol = .513 mol =L 58.5 gm L
513mmol/L