ch101lab final outline

# ch101lab final outline - CH 101-Lab Final Exam Experiment#1...

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CH 101-Lab Final Exam Experiment #1: Measurements of Atoms and Molecules in Solids, Liquids, and Gases I. Introduction: The Idea of the Experiment a. Prepare a monolayer film of oleic acid b. Measure length of long molecule with ruler c. Find avogadro’s number d. Estimate and quick calculations II. Measurement of Atomic Size In Solids. Estimates in the Cubical Atomic Model a. The calculation of an atomic volume i. Molar Mass = Volume times density (M=V·ρ) ii. One mole sample, N A =6.022·10 23 iii. Volume of atom = Volme of sample/# of atoms (V atom = V/N A ) b. Choosing the atomic model i. Volume of atom = length (side) of the cubic model cubed (V atom = (D a ) 3 c. The calculation of the atomic size i. The length of the cubic model = the cubed root of the Molar Mass divided by the density times the number of atoms (D a = ( ) ∛ MρNa ) ii. Density would be given to you while the Molar Mass can be found in periodic table.

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III. Deeper Look: Packing in Solids. The Spherical Atomic Model. a. The actual total volume of all spherical atoms in the sample, V actual , is less thatn the total volume of the sample, V, because of empty space b/t atoms. b. Total volume of the empty space b/t all the atoms in the sample is V empty . Actual volume = Total volume of sample (V actual = V-V empty ). c. For the Volume of the atom, it’s the actual volume divided by Avogadro’s number (V atom =V actural /N a ). Subbing in V actual , it can be (V atom = (V-V empty )/N A ) d. Also, (V atiom = ((V-V empty )/V) · V/N A ) e. Packing coefficient and it must be less than 1 for solids, α=((V-V empty )/V)=(1-(V empty / V)) f. Subbing in , (V atom =αV/N A ) g. The volume of sphere with diameter D a , V atom =π(D a ) 3 /6 h. Subbing, (D a = ( ) ∛ 6αMπρNa ) IV. Molecular Size is Solids, Liquids and Gases a. Both models are far from the actual molecular shape, general estimate gives quite an accurate value for the molecular size. b. Estimate the size of water molecules, (D = ( ) ∛ αMρNa ) c. Dry ice (sublimation) estimate size and volume of CO 2 ,(V ice = πd ice 2 h ice /4) d. Estimate the percentage of the empy space inside the gas sample δV = [(V balloon -V dry ice )/V balloon ]·100%.
V. Esperiments with Monolayer Film of Oleic Acid. Measurements of the Molecular Size and Avogadro’s Number a. Surface-acitve substance or a surfactant b. Hydrophilic- water attracting c. Hydrophobic- water repelling d. Calibration of the pipet i. Volume of drop = 1 / # of drops, V

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ch101lab final outline - CH 101-Lab Final Exam Experiment#1...

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