Three watch glasses are put under a paper cam. A brown paper towel functions simply too. A brvery own paper towel offers better shade contrast of the liquid spots and the rate of evaporation compared to a white paper towel. A drop of water, a drop of ethanol, and also a drop of acetone are inserted on sepaprice watch glasses or in sepaprice locations of the paper towel and the rate of evaporation is observed. The drop of acetone evapoprices a lot much faster than the ethanol which evapoprices quicker than the drop of water.

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Setting the phase before doing the demonstration: Have students predict which liquid will evapoprice fastest and the slowest. Have students describe their choices.

• Which liquid will evaporate the slowest? The fastest? Exordinary.

What determinants determine just how fastor slow a liquid will certainly evaporate at room temperature?


• It will aid to draw the Lewis structures of each molecule,determine if the molecule is polar or non-polar, and calculate the molecular mass of each compound.
• It will aid to recognize the forms of intermolecular forces of attractivity existing between molecules.

Sample student data table

Rate of evaporation versus form and also stamina of IMF

Type of IMFStrength of IMFRelative Rate of Evaporation
Acetone
Ethanol
Water

Strengths ofIMFsVapor Pressure (kPa) at 20°CMelting Point (°C)
Acetonemedium 28 -95
Ethanolmedium- strong 5.95- 114
Waterstrong 2.33 0.0

Strengths of IMFs
*
Hvap(kJ/mol)
Boiling Point (°C)
Acetonemedium30.3+56.5
Ethanolmedium- strong39.3+78
Waterstrong40.6+100

A set of Power Point Slides to acagency this demonstration is easily accessible in the appropriate food selection.


This demo is probably finest offered as soon as pointing out intermolecular forces. Students often think the molecular mass of a compound is the major factor governing physical properties, such as boiling allude and also evaporation.

Learning Objectives

1. Identification of intermolecular forces operating within liquid samples of water, ethanol, and acetone and the correlation of a physical property, price of evaporation, through the kind and also strength of the IMF in the liquid.


Lead Time
One day of lead time is forced for this project.
Discussion

Acetone evapoprices much much faster than water, even though its molecular mass is more than three times as a lot. Water molecules, in the liquid and solid state, are capable of hydrogen bonding, whereas a arsenal of acetone molecules in the liquid state do not. The reasonably solid hydrogen bonding in between water molecules slows the evaporation price and rises the surconfront stress and anxiety, as shown by acetone's flast drop form on the watch glass. Ethanol exhibits hydrogen bonding in between ethanol molecules however does not evaporate as easily as water.


record camera or overhead projector and display (for a medium to large lecture hall)3 little watch glasses or a brown paper towel3 dropper bottles via stoppers or lids, one containing water, one containing ethanol, one containing acetone

The 3 watch glasses are put on the overhead projector. A drop of water, a drop of ethanol, and a drop of acetone are put on sepaprice watch glasses and also the price of evaporation is oboffered. The drop of acetone evapoprices a lot quicker than the drop of water or the ethanol.

One day of lead time is compelled for this project.


Acetone is exceptionally flammable. Take correct prealerts.Potential Health Effectsof acetone:Inhalation -Inhalation of vapors irritates the respiratory tract. May cause coughing, dizziness, dullness, and headache. Higher concentrations can create main nervous device depression, narcosis, and also unconsciousness.Ingestion -Swallowing small quantities is not likely to produce harmful effects. Ingestion of bigger amounts may produce abdominal pain, nausea and also vomiting. Aspiration right into lungs have the right to produce severe lung damages and also is a medical emergency. Other symptoms are intended to parallel inhalation.Skin Contact -Irritating because of defatting activity on skin. Caprovides redness, pain, drying and cracking of the skin.Eye Contact:- Vapors are irritating to the eyes. Splashes may reason severe irritation, through stinging, tearing, redness and pain.Chronic Exposure -Prolonged or repetitive skin call may produce major irritation or dermatitis.

Ethanol is flammable and have the right to be toxic in amount.

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Thanks to Dr. JulieHaack, Department of Chemisattempt & Biochemistry, University of Oregon Chemisattempt Department, for saying this demo.