Viscosity of Liquids
Qualitative test: Four pipets are filled with different liquids. When the liquids are released, they are observed to flow at different rates.
Capillary length test: Four funnels are filled with water and attached to capillary tubing of various lengths. The longer the capillary tube, the slower the rate of flow of the water.
Measuring relative viscosity: The rate of flow of six different liquids through a Mohr pipet is determined. The experiment is set up so that the times at which the liquid reaches the 0 mL and 3 mL marks on the pipet may be observed. The rate of flow depends on the size and shape of the molecules as well as on the types of intermolecular forces involved.
Bubble: An air bubble moving in a liquid in a test tube is demonstrated
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KITCHEN CHEMISTRY
All of the experiments in this packet (Putter Putty, Blueberry Patch Indicator, Household Density Column, Iron for Breakfast, Color Fun, Viscosity of Liquids, Coke(R)/Diet Coke(R)) may be repeated at home. All experimentation should be done only under adult supervision and following all precautions on the labels of the household chemicals/products used. In addition, you may wish to protect surfaces (table or countertop) and clothing while performing the experiments.
VISCOSITY OF LIQUIDS
The viscosity demonstration consists of four bottles containing household materials and marbles to illustrate the relative thickness of each substance.
Flip the bottles over to start the display.
Bottle #1 contains water. It is the least viscous material.
Bottle # 2 contains honey.
Bottle #3 contains roll-on anti-perspirant.
Bottle # 4 contains hair gel. It is the most viscous.
Viscosity is a measure of how much force is required to slide one layer of the fluid over another layer. Substances which do not flow easily (i.e., the gel) have high viscosity. Substances which do flow easily (i.e. water) have low viscosity.
HOUSEHOLD DENSITY COLUMN
What can you make with Karo® syrup, Dawn® detergent, vegetable oil, and rubbing alcohol? This activity shows you how to create a colorful density column from common items available from the supermarket.
Explanation
All materials have characteristic densities. In this activity you are able to observe the relative densities of household liquids, like syrup, oil, and alcohol, and solids, like lead sinkers, rubber stoppers, and corks. As long as the materials do not react or do not mix, a less dense substance will float on a more dense layer. By adding the solids into the column, you can compare their densities to the densities of liquids by observing the position at which each solid comes to rest. The greater a solid's density, the lower it will sink.
Materials
100mL glass cylinder
15mL of each of the following liquids:
Dark Karo® syrup or maple syrup
Glycerin
Dawn® dishwashing liquid
Water
Vegetable oil
Rubbing alcohol
One or more of the following (small pieces):
Lead sinker
Rubber stopper
Oak
Cork
Pine
Plastic
Procedure
1. Slowly pour about 15 mL each of the following liquids into the glass cylinder, letting the liquid run down the side of the cylinder. Be sure to pour the liquids in the order listed.
Dark Karo® syrup or maple syrup 0=1.37 g/mL
Glycerin O= 1.26 g/mL
Dawn® dishwashing liquid O= 1.03 g/mL
Water O=1.00 g/mL
Vegetable oil O=0.91 g/mL
Rubbing alcohol O=0.87 g/mL
If the liquids are carefully poured, one layer on top of another will form. Most liquids can be poured down the side of the cylinder to minimize mixing. Syrup, however, is best poured in without allowing it to run down the side of the cylinder as it is very sticky.
2. Add the small pieces of solid samples to the density column. You can determine their
relative densities by noting the position at which they come to rest in the column.
When adding the solid samples, do so carefully so that the layers of liquids do not mix .
IRON FOR BREAKFAST
Do you eat small pieces of iron metal for breakfast? You do if you eat cereal that is fortified to meet 100% of the minimum daily dietary requirement of iron. In this activity, you will extract the food grade iron filings from a cereal and examine their properties.
Explanation - Iron (Fe) is an essential element. Every molecule of hemoglobin has four ions of iron in it. Hemoglobin is the compound in red blood cells that carries oxygen from the lungs to the tissues. Hemoglobin causes our blood to look red. A deficiency of iron in the diet results in fatigue, reduced resistance to disease, and increased heart and respiratory rate. A healthy adult needs about 18 mg of iron each day. Dietary iron is found in large amounts in organ meats such as liver, kidney, and heart. It is also present naturally in egg yolks, some vegetables, and shellfish. In these foods, iron is typically present as iron(III) (Fe) ions. Our body absorbs iron in the small intestine in the form of iron (III), which then is reduced to iron(II). Under normal conditions, our body absorbs only 5-15% of the iron in the food that we eat. Vitamin C can increase the amount of iron absorbed into the body. Cereals are fortified with food grade iron filings as a food supplement. This iron is metallic iron (Fe). In the stomach the metallic iron is oxidized and eventually absorbed through the small intestine. If all of the iron from your body was extracted, you would have enough iron to make up only two small nails. This amount is about 5-7 grams.
Materials
A non metallic container - about 500 mL volume
Magnet tape
Tongue depressor
Two Ziploc® plastic bags
1cup of breakfast cereal with 100% of the minimum daily requirement of iron (i.e., Total or Special K)
Water
Procedure
Attach the magnet tape to one end of the tongue depressor, place in a Ziploc® bag and close.
Place the cereal in another Ziploc® bag, crush
Pour the crushed cereal into the container, and cover with water
Use the magnet/tongue depressor, still in the Ziploc® bag, to stir the cereal slurry for about 10 minutes.
Remove the stirrer from the container and observe the fine black iron filings on the outside of the plastic bag.
Return the magnet to the slurry and continue stirring for another five minutes, then observe the additional iron filings that have collected.
(Another excellent way to collect the iron is to stir the slurry on a magnetic stirrer with a Teflon coated stir bar. The filings collect on the stir bar and are very easy to see against the white Teflon.)
PUTTER PUTTY
Materials
Borax Solution 30mL (1g 20 Mule Team® Borax to 100mL water)
Elmer's® School Glue 30mL
Food coloring (optional)
Ziploc® plastic sandwich bag
Objective
To demonstrate properties of polymers and to use the properties of a substance to determine which state of matter it characterizes.
Background
Polymers (poly means "many" and mers means "units") are made by combining many repeating units called monomers (mono means "one"). Polymers are a group of chemicals that are found in many forms in the world around us, including plastics, glue, and the biochemical molecules that make up our bodies. The Elmer's® School Glue is a solution containing long polymer chains. Because these chains are long, they interfere with the movement of each other, causing this solution to be rather thick and to pour more slowly than water. This means the solution is more viscous than water. Viscosity is a physical property of a liquid that describes how well it flows. For example, water and alcohol are described as having a low viscosity because they flow quickly; honey and syrup have high viscosities because they flow much more slowly.
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