Three watch glasses are placed under a paper cam. A brvery own paper towel works simply too. A brown paper towel provides much better color comparison of the liquid spots and the price of evaporation compared to a white paper towel. A drop of water, a drop of ethanol, and a drop of acetone are put on sepaprice watch glasses or in separate locations of the paper towel and the price of evaporation is oboffered. The drop of acetone evapoprices much much faster than the ethanol which evapoprices quicker than the drop of water.

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Setting the stage prior to doing the demonstration: Have students predict which liquid will evaporate fastest and also the slowest. Have students define their choices.

• Which liquid will evapoprice the slowest? The fastest? Exsimple.

What determinants identify how fastor slow a liquid will certainly evapoprice at room temperature?


• It will certainly aid to draw the Lewis structures of each molecule,identify if the molecule is polar or non-polar, and also calculate the molecular mass of each compound.
• It will certainly aid to determine the kinds of intermolecular pressures of attraction present between molecules.

Sample student data table

Rate of evaporation versus form and toughness 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 collection of Power Point Slides to acagency this demonstration is easily accessible in the right food selection.


This demo is more than likely finest offered as soon as discussing intermolecular pressures. Students frequently think the molecular mass of a compound is the significant aspect governing physical properties, such as boiling allude and also evaporation.

Learning Objectives

1. Identification of intermolecular pressures operating within liquid samples of water, ethanol, and also acetone and also the correlation of a physical residential or commercial property, rate of evaporation, through the type and strength of the IMF in the liquid.


Lead Time
One day of lead time is required for this task.
Discussion

Acetone evapoprices much much faster than water, also though its molecular mass is more than three times as a lot. Water molecules, in the liquid and also solid state, are capable of hydrogen bonding, whereas a collection of acetone molecules in the liquid state carry out not. The fairly strong hydrogen bonding between water molecules slows the evaporation rate and also increases the surconfront stress, as evidenced by acetone's flast drop shape on the watch glass. Ethanol exhibits hydrogen bonding between ethanol molecules however does not evapoprice as quickly as water.


record camera or overhead projector and display (for a tool to big lecture hall)three tiny watch glasses or a brvery own paper towelthree dropper bottles through 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 separate watch glasses and also the price of evaporation is observed. The drop of acetone evapoprices much faster than the drop of water or the ethanol.

One day of lead time is compelled for this task.


Acetone is extremely flammable. Take correct prewarns.Potential Health Effectsof acetone:Inhalation -Inhalation of vapors irritates the respiratory tract. May cause coughing, dizziness, dullness, and also headache. Higher concentrations can produce main nervous mechanism depression, narcosis, and unconsciousness.Ingestion -Swallowing little amounts is not most likely to create harmful impacts. Ingestion of larger amounts might develop abdominal pain, nausea and also vomiting. Aspiration into lungs have the right to produce significant lung damage and is a medical emergency. Other symptoms are intended to parallel inhalation.Skin Contact -Irritating because of defatting activity on skin. Casupplies redness, pain, drying and also cracking of the skin.Eye Contact:- Vapors are irritating to the eyes. Splashes may reason severe irritation, through stinging, tearing, redness and pain.Chronic Expocertain -Prolonged or repetitive skin contact might produce major irritation or dermatitis.

Ethanol is flammable and also deserve to be toxic in quantity.

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