Chemistry Honors – Classes 49 & 50

Dates

• Period B: Wednesday, April 29th
• Period D: Wednesday, April 29th
• Period G: Friday, May 1st
• Thursday, April 30th – Library Research

Lab Activity – Intermolecular Forces

• Overview – students will use a stainless steel temperature sensor to determine the effects of molecular size and shape on the strength of intermolecular forces for different alcohols within the same homologous series and between isomeric pairs.

Lab Objectives – Students will be able to:

• explain why evaporation causes a decrease in temperature.
• describe the relationship between evaporation rate and the strength of intermolecular forces of attraction among molecules.
• describe the relationship between the size of molecules in a homologous series and the strength of intermolecular forces of attraction between them.
• describe the influence the shape of a molecule has on its vapor pressure by comparing the evaporation rates of two isomeric alcohol pairs.

Method – Procedure

• Compare the rate of evaporation for the different liquids to determine the relative strengths of the intermolecular forces of attraction

Liquids Used

• Methanol (CH₃OH)
• Ethanol (C2H5OH)
• Propanol (C₃H₇OH)
• Acetone (CH₃COCH₃)

Materials Needed

• Graduated cylinder, 10-mL
• Test tubes (6), 15-mm x 100-mm
• Test tube rack
• Stoppers (6), to fit the test tubes
• Wash bottle and waste container
• Masking tape (2), 6-cm strips

Final Submission

• export the work as ONE FILE
• submit to the Schoology LW14

Molecule Pictures

Acetone

Ethanol

Methanol

Propanol