CHEM 241

lab 7: what sort of condenser should you use and why? - correct answers a water condenser instead of an air condenser because it is better at preventing your solvent and or products from evaporating how can you reduce the health risk of silica gel? - correct answers keep it wet with solvent so less powder gets in the air, handle the gel in the fume hood, I'm some gel spills wipe it with a wet paper towel, wear PPE What is true about mixing liquids in a separatory funnel? - correct answers...

History of chromatography (ch 23) - correct answers -Greek word "chromatus" for color -Tswett (1903) first separated plant pigments Applications - correct answers Breast milk, water analysis, urinalysis for drug doping Goals of separation - correct answers Recovery of product, purity of product Type, SP, MP - correct answers 1. Adsorption: one polar substance sticks to another polar substance. Solid SP, gas or liquid MP 2. Partition: dissolving of 2 similar liquids. Liquid SP, gas o...

How do you extract the amine - correct answers 1. Dissolve in ether 2. add HCl to make amine soluble in water (not ether) 3. Extract aqueous layer 4. add NaOH 5. collect precipitate What layer will the amine be found in (ether/ aqueous) - correct answers aqueous Which layer is the aqueous layer - correct answers bottom which layer is the ether layer - correct answers top how can you tell which liquid will be which layer - correct answers density how do you extract the amine - ...

Extraction - correct answers Transfer of a solute from one phase to another Eluent - correct answers Fluid entering the column Partition Chromatography - correct answers Separation based on solute dissolving into stationary liquid Ion-Exchange Chromatography - correct answers Separation based on charge, stationary phase is made of either negatively or positively charged beads Size Exclusion Chromatography - correct answers Separation based on molecular size, larger molecules elute fi...

How do transmittance, absorbance, and molar absorptivity differ? Which one is proportional to concentration? - correct answers *transmittance* = (P/P0) *absorbance* = log(T) absorbance is proportional to concentration Why is it most accurate to measure absorbances in the range A = 0.3-2? - correct answers If absorbance is too high, too little light reaches the detector for accurate measurement If absorbance is too low, there is too little difference between sample and reference for a...

Crystalline solids have what? - correct answers have highly ordered structures In liquids, the active IMF are...? - correct answers strong enough to hold molecules relatively close together but not strong enough to keep molecules from moving past each other In which of the following molecules is H bonding likely to be the most significant component of the total IMF? - correct answers CH3OH What substance has London only? - correct answers Kr What substance has dispersion only as its ...

A. Will your compound be more soluble in hot or cold solvent? - correct answers It will be more soluble in hot solvent because increasing temperatures increases molecular movement, causing more collisions between the water molecules and the solid compound. B. You have a solution of NaCl and water. You heat the solution to boiling and observe bubbles forming in the solution, and vapor escaping the flask. What is the identity of the bubbles and the vapor? - correct answers The bubbles is the wa...

Goals of Separation - correct answers recovery of product, purity of product Types of Chromatography - correct answers Adsorption - SP: solid, MP: gas/liquid Partitioning - SP: liquid, MP: gas/liquid Ion-Exchange - SP: bonded anion/cation, MP: liquid Molecular Exclusion - SP: has pores, MP: liquid Affinity - SP: antigen/antibody interactions, MP: liquid Electrophoretic - no SP Solvent Extractions based on - correct answers Some solvents are not miscible; "like dissolves like"; less ...

Extraction - correct answers Transfer of a solute from one phase to another Eluent - correct answers Fluid entering the column Partition Chromatography - correct answers Separation based on solute dissolving into stationary liquid Ion-Exchange Chromatography - correct answers Separation based on charge, stationary phase is made of either negatively or positively charged beads Size Exclusion Chromatography - correct answers Separation based on molecular size, larger molecules elute fi...

What are the wavelengths of visible light? - correct answers 400 - 800 nm How do X-Rays affect electrons? - correct answers Electronic Transitions of Core Electrons (Breaks chemical bonds and ionizes molecules) How does UV- VIS affect electrons? - correct answers Electronic Transitions of Valence Electrons (Vibrational + Rotational as well) How does IR affect electrons? - correct answers Vibrational Transitions (Rotational as well) How do Microwave waves affect electrons? - correct a...