Five Layer Density
Five-Layer Density Column
A density column consists of layers of liquids of different densities which do not mix with each other, and which are clearly distinguishable from each other. The highest density material is at the bottom of the column, and as you proceed up the column, the density of each successive layer decreases, with the lowest density layer on top. Three methods for construction of a five-layer density column are discussed in this write-up. All methods use the same five liquids. • Method 1 gives the names of the liquids and the order for adding them, and its goal is to directly construct the density column without any experimentation. • Method 2 assumes names and densities of the five materials to be unknown, and involves open-ended experimenting, with few instructions, to construct the column. • Method 3 also assumes names and densities of the materials to be unknown, and outlines a systematic way to approach the experimentation involved in constructing the column.
METHOD 1
Obtain a clear plastic container whose size meets your needs, and carefully add appropriate amounts of the following materials in the order specified (the first material listed is the most dense, and should be added first: water -- color with an appropriate amount of food color before pouring canola oil -- don 't add food color (it won 't dissolve in oil) 60% isopropyl alcohol -- you can buy 70% isopropyl at drug stores and grocery stores -- it 's used as rubbing alcohol and disinfectant -- you then have to dilute it to make it 60% -- add 2 ml of water to every 10 ml of alcohol, or 20 ml of water to every 100 ml of alcohol -- before pouring, color with an appropriate amount of food color different from the first one mineral oil -- baby oil is mineral oil, and can be used here, but ordinary mineral oil is easily obtained at pharmacies and is cheaper -- don 't add food color (it won 't dissolve in oil) 91% isopropyl alcohol -- you can buy 91% isopropyl at most drug stores, and
A density column consists of layers of liquids of different densities which do not mix with each other, and which are clearly distinguishable from each other. The highest density material is at the bottom of the column, and as you proceed up the column, the density of each successive layer decreases, with the lowest density layer on top. Three methods for construction of a five-layer density column are discussed in this write-up. All methods use the same five liquids. • Method 1 gives the names of the liquids and the order for adding them, and its goal is to directly construct the density column without any experimentation. • Method 2 assumes names and densities of the five materials to be unknown, and involves open-ended experimenting, with few instructions, to construct the column. • Method 3 also assumes names and densities of the materials to be unknown, and outlines a systematic way to approach the experimentation involved in constructing the column.
METHOD 1
Obtain a clear plastic container whose size meets your needs, and carefully add appropriate amounts of the following materials in the order specified (the first material listed is the most dense, and should be added first: water -- color with an appropriate amount of food color before pouring canola oil -- don 't add food color (it won 't dissolve in oil) 60% isopropyl alcohol -- you can buy 70% isopropyl at drug stores and grocery stores -- it 's used as rubbing alcohol and disinfectant -- you then have to dilute it to make it 60% -- add 2 ml of water to every 10 ml of alcohol, or 20 ml of water to every 100 ml of alcohol -- before pouring, color with an appropriate amount of food color different from the first one mineral oil -- baby oil is mineral oil, and can be used here, but ordinary mineral oil is easily obtained at pharmacies and is cheaper -- don 't add food color (it won 't dissolve in oil) 91% isopropyl alcohol -- you can buy 91% isopropyl at most drug stores, and
References: Sarquis, Jerry L.. Mickey Sarquis, John P. Williams, Teaching Chemistry with Toys, TAB Books, 1995. See Frustration Bottles, pp. 239-243. Borgford, Christie L., Lee SR. Summerlin, Chemical Activities; Teacher Edition, American Chemical Society, 1998. See Layers of Liquids, pp. 27-28. Five-Layer Density Column.....9/29/05 © 2005 Exploratorium, www.exploratorium.edu 5 Don Rathjen....Exploratorium Teacher Institute....3601 Lyon St., San Francisco, CA 94123...donr@exploratorium.edu