CHM 110 - CHEMISTRY AND ISSUES IN THE ENVIRONMENT


List of Chemicals for the Home Labs
Home Laboratory #1
C. Ophardt, Elmhurst College, c. 2002


PHYSICAL & CHEMICAL PROPERTIES AND CHANGES OF HOUSEHOLD SUBSTANCES

Part 1: PRE-LAB: ELEMENTS & COMPOUNDS USED IN EVERYDAY LIVING

At home collection of lab data (5 points)

ELEMENT INVENTORY: Find examples of as many elements and compounds as possible in the entire Periodic Table. Look at the ingredient's lists on foods, drugs, and other house hold items. Baby formula has about 15 elements listed. Look for the names of the chemicals that seem to have the name of a chemical element as part of the name. There are many names which you will not recognize - simply ignore them. In other cases you may list the names of compounds and elements which you know from common knowledge such as gold and silver in jewelry.

Do not make duplicates in element names or symbols, but make a fairly exhaustive listing because we will use the list for several activities such as writing the formula. Each element may be listed only once, even though you may find it numerous times. Make the following Element Inventory Table :

EXAMPLE INVENTORY TABLE

Common substance

Chemical name

Element Name

 Symbol

Element Count
 Water  -  Hydrogen  H  1
 Water - Oxygen O 2
 Baking Soda Sodium Bicarbonate  Sodium Na 3
 Baking Soda  Sodium Bicarbonate  Carbon C 4
 Air oxygen & nitrogen  Nitrogen N 5



On the far right side for the element count, simply count how many different elements have been found, count only one example of each element. For example in water are the elements hydrogen and oxygen. In Baking Soda, the elements sodium and carbon are found. In air, nitrogen and oxygen are found, but do not list oxygen a second time, list nitrogen instead. From these three substance five elements are counted.
Dr. O Help: More Examples

This element inventory listing is worth 5 points if you find 30 elements. 25 elements = 4 points; 20 elements = 3; 15 or less elements = 2.

QUES. 1: Make the following Element Inventory Table :

(It is not necessary to make a fancy table, you may just use spaces following the headings below.)

Count, Common Substance, Chemical Name, Element Name, Element Symbol

1, water, -, oxygen, O
2, water, -, hydrogen, H

 



Laboratory Introduction

Chemical and physical properties can be used to help identify compounds in solids such as, sodium carbonate, sodium bicarbonate, sodium chloride, calcium carbonate, and sodium hydroxide. The compounds to be tested for, as well as, all the reagents used to identify them are readily available in most drugstores, supermarkets, or variety stores. The tests require no more than a few small cups, a measuring cup, an eye dropper, and a spatula or measuring spoon.

Chemicals Chemical List

The chemicals are all available as household products. The white solids to be used in this lab are listed in Table 1 along with their sources. These substances can be taken directly from their packages, except for the calcium carbonate which must be powdered. You will need a minimum of 3 compounds or mixtures from the list below plus 2 where online data are given (Epsom salt and baking powder).

Table 1.
Compound Name, Formula, Source of Compound


"Pure" Compounds:

Sodium chloride, NaCl, Plain table salt
Sodium bicarbonate, NaHCO3, Baking soda
Sodium carbonate, Na2CO3, Washing Soda Detergent e.g. Arm & Hammer
Calcium carbonate, CaCO3, Calcium supplement tablets (TUMS)
Sodium Aluminum dihydroxide carbonate, NaAl(OH)2CO3, ROLAIDS
Sugar

Mixtures:

Any solid detergent
Any solid antacid


EXPERIMENTAL PROCEDURES
PART 2: PHYSICAL PROPERTIES AND CHANGES
Combination of online and at home collection of data (6 points)


The requirement is to do five compounds total - use any 3 of the above compounds or mixtures, plus 2 compounds given online for full credit.
O r do five compounds of your own.
(Minus 1/2 point for each not done.)


Proc. 1: Solubility Tests:

Each of the five solids is first tested for solubility in water.

To perform the solubility test, use a spatula or knife tip to obtain less than an aspirin tablet sized amount of material, (too much solid will obscure the results) and place it in a small cup with about 1-2 teaspoons (5 ml) of water. Do this with all three of the solids in separate cups. Mix and stir well for several minutes to see whether the solid will dissolve, if necessary add more water. SAVE the solutions for further testing.

Try to distinguish between complete dissolving - clear solution - These are called SOLUBLE;
to almost dissolved - may have a slight cloudiness left- listed as partially SOLUBLE;
to lots of solid remaining, very cloudy - listed as INSOLUBLE. Dr. O, Help!

Compounds that dissolve in water undergo a physical change. The chemical formula remains intact. If the water is evaporated, the original compound is recovered.

Online data for: These two count for 2 of the five required above.

 

Epsom Salt
Baking Powder

Record the observation results in a table format as follows. Dr. O, Help!

QUES. 2: OBSERVATION TABLE for Solubility Tests

On the Observation Table record the observations and results of the tests. For each compound or mixture tested, record the name, and the formula (if given), any significant observations - what did you see???, and results or conclusion of the test based upon the observation.

Example: Aspirin; (formula not given); white solid dispersed in water, milky, some particles float; result = insoluble.

Results for five more samples:

Dr. O, Help!



QUES. 3: Match definitions and examples:

 Pure Compound definition  a. combination of two or more subtances
 Mixture definition  b. different "states" of matter, visually distinguishable
 Homogeneous mixture definition  c. single substance with a definite composition, two or more elements
 Heterogeneous mixture definition  d. uniform through out, clear solutions, all in one "state" of matter
 Pure Compound example  e. baking powder and water
 Solid Mixture   f. sugar and water
 Homogeneous example   g. sugar by it self
 Heterogeneous example  h. detergent


Proc 2: Evaporation of a Solution:

Do the following procedure on ONE of the solutions that is soluble or almost soluble, such as the salt or sugar solution. Pour the solution into a metal sauce pan and evaporate the water using the the burner on the stove. After the water has been evaporated to dryness , a residue should remain. DO NOT OVER HEAT - AS THE SUGAR MIGHT BURN. After the pan has cooled, you might try the taste test to identify this residue. Moisten your finger, touch the residue, and cautiously taste it.

QUES. 4: A physical change occurs when the composition of a substance remains the same. (True or False)

QUES. 5: A chemical change occurs when the composition of a substance remains the same. (True or False)

QUES. 6: Evaporation is is an example of a chemical change. (True or False)

QUES. 7: Salt or sugar dissolving in water is a physical change. (True or False)

 

 

Proc. 3. MIXTURE OF LIQUIDS - A SIMULATED OIL SPILL



Make a simulated oil spill by putting 2 -3 table spoons (10 - 15 ml) of mineral or vegetable oil into a large cup. Then add about 3/4 cup of water.

Oil Spill Cleanup

QUES. 8: The oil stay on the bottom of the water. (True or False)
QUES. 9: The oil is more dense than the water. (True or False)
QUES. 10: Solubility behavior and density behavior of oil and water is: a chemical or physical property ?

QUES. 11: a) Devise a method to remove the oil from the top of the water. Available devices are eye droppers to simulate a vacuum type device, paper towels, pieces of cotton balls, detergent, anything else that you can think of. Carefully record and describe which methods were used to separate the oil from the water.




b) Would the method that you used to clean up an oil spill have any applicability on a large body of water such as a river or ocean? Explain.

PART 3. Chemical Reactions (4 points)

****All Data for Part 3 is given online****
****You do not actually have to complete these procedures. Dr. Ophardt did them for you and took pictures of the results. You should read the procedures to see what was done, record the data, and answer the questions.*****

Procedure 1: WHICH METALS REACT WITH ACIDS?

INTRODUCTION:

Did you know that pennies come in two varieties? Pennies minted before 1982 are made entirely from the metal element called copper. Pennies minted after 1982 contain a core made from the metal element zinc and the outer layer is made of copper. In this experiment, you will discover the chemical properties of zinc and copper metals, with hydrochloric, HCl, from Sno Bol toilet bowl cleaner.

1. First use a wire cutter type pliers or an old scissors to make five or six very thin cuts on the edges of a 1983 (or newer) penny. Or use a file to remove small amount of copper metal from the edges of the pennies. The cuts should expose a silvery metal which is zinc beneath the copper layer.

 

3. Prepare one cup and fill half full with Sno Bol toilet bowl cleaner (use the thin rather than the thick variety if possible) or any other toilet bowl cleaner, which contains hydrochloric acid.

4. Next put the one penny into the small plastic cup containing the Sno Bol toilet bowl cleaner.

5. Make and record observations during the first few minutes. Look for bubbles of hydrogen gas coming from the edges of the penny or the aluminum foil. Are the gas bubbles coming from the copper metal or the zinc metal or the aluminum metal?

6. This chemical reaction of the acid with the penny takes several days to complete.

OBSERVATIONS AND RESULTS on metals with acids:

Write details of the observations, both immediately and after 1 or 2 days.

Sno Bol + penny

 

QUES. 12: Which metal copper or zinc reacts with the hydrochloric acid?

QUES. 13: Which metal copper or zinc do not react with the hydrochloric acid?

This shows that metals may have different chemical properties towards the acids.

QUES. 14: What is the name of the element in the gas bubbles? Oxygen, Hydrogen, Chlorine

 

EXPLANATION:

These observations are an example of a chemical properties and reactions. Various elements in the original substances undergo a chemical reaction where elements in compounds rearrange and change "forms" - metals into ions; and ions into the element form.

The outside coating of copper metal does not react with hydrochloric acid, HCl, in the toilet bowl cleaner. The zinc metal core does react with the acid, hydrogen ions, H+, to produce zinc ions, chloride ions, (which are invisible in the water) and hydrogen gas bubbles (which escape into the air). The element zinc metal turns into soluble zinc ions. The final result is a "hollow" penny. Two elements change form: zinc metal changes to zinc ions and hydrogen ions change into the diatomic hydrogen gas form.

REACTIONS:

Cu metal + HCl ===> No reaction

Zn metal + 2 HCl ===> Zn+2 ions + 2 Cl- ions + H2 gas

Procedure 2: Reaction of Zinc and Iodine

Reaction Graphic of zinc and iodine

The reaction in this case is between two elements, zinc metal and iodine. Both look sort of grayish in the photo. The reaction is started between the dry powders by adding a few drops of water. The reaction occurs as a combination reaction between the two elements to produce a single compound. During the reaction zinc metal gives two electrons to two iodine atoms to produce zinc +2 ions and iodide -1 ions.

The reaction is: Zn metal + I2 ----> ZnI2

The reaction between the two elements to produce zinc iodide is very exothermic. Some of the unreacted iodine solid is heated to a gaseous iodine which is purple in color.

QUES. 15: A molecule is only defined as the simplest part of a compound with two or more atoms. (True or False)

QUES. 16: For an exothermic reaction, heat is given off in the process. (True or False)

QUES. 17: The fact that unreacted iodine changes to gaseous iodine is a: chemical or physical change?

 

Procedure 3: Reaction of Efferdent and Alka-Seltzer with Water

 

Reaction Graphic of Alka-Seltzer

Reaction Graphic of Efferdent

The reactions in both of the above cases start when a solid tablet is dropped into water. The chemicals in dry solid form must dissolve in the water before a reaction may take place. In both cases gas bubbles are observed. A flaming or glowing splint is used to test for the identity of the gases.

Reactions:

Alka-Seltzer: (Baking soda or sodium bicarbonate) NaHCO3 + Citric acid ---> CO2 + H2O + Sodium Citrate
Efferdent: (sodium perborate - a source of hydrogen peroxide) = H2O2 + catalyst ---> O2 + H2O

QUES. 18: Define chemical property. Then use this definition to describe the difference in behavior toward the falming splint for both gases in the above examples.

 

QUES. 19: Graphic of Baking Powder - Revisited

Based upon the observations in the graphic, do you think that putting baking powder in water represents a physical or chemical change? Explain your answer.