Pre-AP Chemistry
Instructor: Mr. Malasky
Name __________________________________________ Period ______ Due Date ___________
Laboratory Activity: Properties of Calcium Acetate
Background
Mixing a concentrated calcium acetate solution with alcohol produces a type of colloid called a
gel. When this gel is burned, it can be used as a heat source similar to commercial Sterno. The gel is more
desirable for storing and transporting. It is believed that the calcium acetate traps the alcohol is a flexible
network lattice as a gel. The formation of the gel is a physical phenomenon, not a chemical reaction. When the
alcohol in the gel burns, it reacts with oxygen in the air to produce carbon dioxide and water. Calcium carbonate
and acetone are produced due to heating the calcium acetate in the gel.
Calcium acetate is an interesting compound in terms of solubility. The solubility of calcium acetate is
37.4g/100 g in cold water, but drops to 29.7 g/100g in hot water. Thus it is an exception to the general rule that
solubility increases with increasing temperature. It is easy to observe calcium acetate become soluble as the
temperature gets cooler, and crystallize as it gets warmer.
Calcium acetate can be produced in a double replacement reaction from vinegar (acetic acid) and
calcium carbonate (limestone, marble, chalk). A solution of calcium acetate can be returned to solid crystals by
removing the water.
Materials
100 ml beaker
graduated cyl, 10 ml, 50 ml
ringstand
balance
evaporating dish
thermometer
test tube holder
calcium acetate (s)
sodium chloride (s)
ethyl alcohol
tube of calcium acetate (aq)
calcium carbonate (s)
household vinegar
hot plate
warm beaker bath
ice beaker bath
burner
test tube w/stopper
400 ml beaker
stirring rod/spatula
Methods
1. Weigh out 1.0 g of calcium acetate and place in a test tube.
2. Measure 3.5 ml of deionized water in a 10 ml cylinder and add to the test tube. Stopper and shake.
(Not all of the solid will not dissolve)
3. Add a pinch of sodium chloride to the tube. Stopper and shake again.
4. Transfer the solution to a 100 ml beaker. Measure 24 ml of ethyl alcohol in a 50 ml cylinder, and
add to the beaker. Stir. Note the new properties. (#1)
5. Transfer the contents to the evaporating dish with a spatula, place the dish on the base of the
ringstand, and ignite the contents using the Bunsen burner. Describe the burning process. (#2)
6. Note the formation on the inside of the evaporating dish. (#3) After burning for a while, extinguish
by placing a beaker over top of the evaporating dish.
7. Wash any remaining gel down the sink with plenty of water.
8. Get a test tube of saturated calcium acetate solution. Place in a warm water beaker bath (deionized)
on the hot plate. Note the temperature (#4) in the test tube when the solution has solid particles
suspended. Transfer the test tube to an ice bath and note the temperature when the dissolving of the
solid occurs (#4). Return this tube to the racks provided, do not discard the solution.
9. In a clean evaporating dish, add 20 ml of vinegar to 0.83 g of calcium carbonate. Stir until evidence
of a reaction ceases. Note changes (#5). Gently warm on the hotplate until solid crystals remain. Note the
final product (#6). Wash the product down the sink with water.
over------
Observations (60 pts)
1. properties of gel produced-
2. burning process of gel-
3. formation on inside of dish-
4. temperature when solid forms
temperature when solid dissolves
_________ oC
_________ oC
5. vinegar + calcium carbonate reaction-
6. calcium acetate product-
Questions (40 pts)
1. What is the chemical formula for calcium acetate?
2. Why is the sodium chloride added to the calcium acetate solution?
3. What is chemical name of the “residue” on the inside of the evaporating dish after burning the gel?
4. If the gel were to sit out uncovered for several days, what would happen?
5. What compound is produced from procedure 9 besides calcium acetate? What happens to this
compound?