Wednesday, March 7, 2012

Percent Composition, Empirical and Molecular Formulas, Hydrates take 2

Evaporation and Intermolecular Attractions

Goal:
   The goal in this lab is to study temperature changes caused by evaporation. The temperature changes will be related to the strength of intermolecular forces of attraction. The results will predict, then measure, the temperature change for several other liquids. Also we will study the molecular structures of alkanes and alcohols for the two intermolecular forces known as hydrogen bonding and dispersion forces.

Material:
   Mac Computer                                                              two small rubber bands
   methanol                                                                       masking tape 
   Serial Box Interface                                                      ethanol
    Data Logger                                                                 1-propanol
   Two Vernier Temperature probes                                 1-butanol
   6 pieces of filter paper                                                   n-pentane
   n-hexane

Procedure:
    First prepared the computer so we could get our data. Then we gathered all the materials and started the experiment. Wrapped probe 1 and probe 2 with filter paper and to hold it together we used the rubber bands. Then we put probe 1 in methanol and second one in ethanol. Let them soak for about fifteen seconds. After that we took the probes out of the containers and  put them at the edge of the table with masking tape and recorded the temperature. To get the results we had the lower temperature subtracted the higher one and that's how we were able to determine the temperature changes for the other ones.

Methanol and Ethanol

Heptane and Hexane

Propanol and Butanol     





     Data:
                                                       


Analyzing the Data:
       
            In the alcohols studied (methanol and ethanol) Methanol had the strongest intermolecular forces attraction and ethanol had the weakest. Methanol has the ^t of 21.9 and ethanol has the ^t of 14.3, making methanol a stronger intermolecular force attractions. (^= triangle)
            In alkanes studied (pentane and hexane) Hexane had a stronger intermolecular force attraction than pentane because the ^t for hexane is 17.5 and pentane is ^t7.5, making hexane with the stronger intermolecular force attraction.