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Concentration Slides

Concentration Slides. Mixtures and Solutions. Mixtures – two or more components physically intermixed but not chemically bonded Solutions – homogeneous mixtures of components Solvent – substance present in greatest amount Solute – substance(s) present in smaller amounts

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Concentration Slides

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  1. Concentration Slides

  2. Mixtures and Solutions • Mixtures – two or more components physically intermixed but not chemically bonded • Solutions – homogeneous mixtures of components • Solvent – substance present in greatest amount • Solute – substance(s) present in smaller amounts • Colloids - heterogeneous mixtures whose solutes do not settle out • Suspensions - heterogeneous mixtures with visible solutes that settle out

  3. Concept of Concentration • Concentration refers to the amount of a substance in a given volume • A critical concept to master

  4. Units of Concentration • Percent – parts per hundred • PPM – parts per million • PPB – parts per billion • Molarity – moles per liter • Molality – moles particles per kg solvent • Mass/volume • g/ml (gram per milliliter) • mg/ml (milligram per milliliter ) • g/ml (microgram per milliliter) • Mass/Mass • mg/kg body mass • g/kg body mass

  5. Molecular Weight, Moles & Molarity • Molecular weight • The mass of a mole of atoms or molecules • Has units of g/mole • = atomic weight of an atom in grams • 1 mole of C= 12 g OR C is 12g/mole • Molecule’s molecular weight = sum of the atomic weights of its atoms • 1 mole of H2O = 1g + 1g + 16g = 18 g • MW of H2O = 18g/mole

  6. Molecular Weight, Moles & Molarity • What’s a mole?? • The number of molecules in the gram molecular weight of that molecule • Always 6.02 x 1023 • This magical number is Avogadro’s Number • MW of C = 12 • there are 12g C/mole C • there are 6.02 x 1023 C atoms in 12g of C • MW of H2O = 18 • there are 18g H2O/mole H2O • there are 6.02 x 1023 H2O molecules in 18g of H2O

  7. Molarity – The Standard of Chemical Concentration Terms • Molarity = moles of solute per liter (L) of solvent • Abbreviated with M • A 5M NaCl solution contains 5 moles of NaCl molecules per liter of solution • So 1 L of a 5 M NaCl solution contains 5 moles or 3.01 x 1024 molecules of NaCl

  8. Calculating Molarity • Chemical formula for glucose is C6H12O6 • MW = 180 g/mole • What is concentration of glucose in a can of coke? • 42g of glucose/355ml H2O • How many moles of glucose? • 42g / 180g/mole = 0.233 moles • How many liters of coke? • 355 ml / 1000ml/L = 0.355 L • How many moles/liter? • 0.233 moles/0.355 L = 0.656 M

  9. Examples using Molarity • Ion concentrations in cells & body fluids • [Na] = 0.15M outside cells & 0.015M inside cells • [K] = 0.005M outside cells & 0.15M inside cells • Molar is often converted to millimolar (mM) • M = moles/L • mM = millimoles/L • 0.15M = 150mM • Simply multiply M by 1000 to convert M to mM

  10. Mass/Volume & Percent Concentration Terms • Many molecules in the body are measured in mass/volume • Normal glucose = 100mg/dL • or 100mg/100ml • or 1mg/ml or 1g/L • or 0.001g/ml • or 0.1g/100ml • Cholesterol should be below 200mg/dL • or 0.2g/dL • or 0.2g/100ml • Many substances are described in percentages • Percentage is g/100g or g/100ml • Blood [glucose] would = 0.1% • Blood [cholesterol] would = 0.2%

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