Using freezing point depression to find molecular weight Mass of weighing paper (for solvent): 0.37 g
Mass of lauric acid + weighing paper: 3.37 g F. P. lauric acid: 43.2°C Kf (lauric acid): 3.9°C/m
Mass of weighing paper (for solute): 0.40
Mass of unknown solute + weighing paper: 0.70 g F. P. of mixture with unknown #1 (benzoic acid): 40.0°C Theoretical MW: 122 g/mol; experimental MW: 122 g/mol F. P. of mixture with unknown #2 (camphor): 40.7°C Theoretical MW: 152 g/mol; experimental MW: 156 g/mol F. P. of mixture with unknown #3 (stearic acid): 41.8°C Theoretical MW: 284 g/mol; experimental MW: 278 g/mol
a. Calculate molality (m), in mol/kg, using the formula Delta t=Kf*m . The Kf value for lauric acid is 3.9°C•kg/mol.
b. Calculate moles of benzoic acid solute, using the molality and the mass (in kg) of lauric acid solvent.
c. Calculate the experimental molecular weight of benzoic acid, in g/mol.
d. Determine the accepted molecular weight of benzoic acid from its formula, C6H5COOH.
e. Calculate the percent discrepancy between the experimental and accepted values.

The covalent compound acetylene, which is the fuel of the oxyacetylene torch used by welders, has the molecular formula c2h2. the covalent compound benzene, a commercial solvent, has the molecular formula c6h6 each of these covalent compounds contains carbon and hydrogen atoms in a one-to-one ratio. would it be correct to write the chemical formulas of each as ch? explain.

Straightforward questions answered in the powerpoint slidesreaction: heating the starting materials under refluxwhat does it mean to heat under reflux? why do we choose water as the reflux solvent? what are boiling chips used for? why do we put a condenser on top of the reaction? why do we add heat and let the reaction stir for 30 minutes? why do we add sulfuric acid to the reaction after it cools as opposed to when it’s still hot? separation: filtration of precipitatewhy don’t we do an aqueous and organic extraction in the separatory funnel? why do you rinse the salicylic acid on the filter with ice cold water? purification: recrystallization of salicylic acid (no hot filtration needed)what is the difference in the amount of room temperature water vs. boiling water needed to dissolve the salicylic acid (assume a 1.2 gram yield of salicylic acid)? remember, in the lab if you need x ml of boiling water to dissolve a solid, then you should add a little more (definitely no more than 1.5 times the theoretical amount) to ensure it doesn’t recrystallize prematurely.analysis: melting point of salicylic acidwhat can you conclude if the melting point of the salicylic acid you just synthesized is 152-155oc and the 1: 1 mix of your product and “synthetic” salicylic acid is 151-154oc?

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