CHM 110 - CHEMISTRY AND ISSUES IN THE ENVIRONMENT

List of Chemicals for the Home Labs

Home Laboratory # 5
C. Ophardt, Elmhurst College, c. 2002

POLLUTION DILUTION

PRE-LAB: PERSONAL/HOUSEHOLD WATER RESOURCE USE - (5 points)

OBJECTIVES:

1. Calculate/estimate the resources that you or your household uses on a daily or yearly basis.
2. Appreciate the fairly large amounts of resources needed to support your life-style.
3. Recognize methods for decreasing your use of resources.

INTRODUCTION:

In this exercise, you will be introduced to various water resources which are used to support the lifestyles that we are accustomed in the United States. You will calculate the amount of water resources that you personally use, as well as, the amounts calculated on a per capita basis. The per capita amounts are used indirectly by you because of the manufacturing, industrial, and agricultural activity needed to support society in general. For the per capita calculations, assume that the population of the United States is 250 million. Take whatever figure is given for the entire U. S. and divide by 250 million to get the per capita amount.

INVENTORY # 1: WATER USED TO TAKE A SHOWER or BATH

 

Does a shower or bath take more water?

Volume of the Pail: Find a small pail and use a large measuring container to find the volume of the pail.
Helpful conversion units: 2 cups = 1 pint; 2 pints = 1 quart; 4 quarts = 1 gallon; 1 quart = 0.946 liters.

Show method used to find the volume of the pail.

VOLUME OF PAIL: __________________

Turn on the shower faucet to the normal amount of water that you use. Measure the time it takes to fill the pail with water when you hold it up close to the shower head/faucet. Then measure the total time that you normally stay in the shower.

OR (do one or the other)

use the same procedure to measure water to fill the bath tub.

QUES. 1: DATA: SHOWER or BATH

Volume of Pail ___________

TIME TO FILL PAIL: ___________

TOTAL TIME FOR SHOWER OR BATH: ___________

Calculate how many pails of water would be filled during the time it takes for a shower or to fill the bath tub. Finally calculate the volume of water in gallons used for a shower or bath - show work.

PAILS OF WATER ___________

GALLONS OF WATER PER SHOWER OR BATH: ___________

QUES. 2: Count the number of showers/baths on the average per day in your house. Then calculate the volume of water used per day and then per year - show work.

NUMBER OF SHOWERS/BATHS PER DAY: _________________

VOLUME OF WATER USED PER DAY: ________________

VOLUME OF WATER USED PER YEAR: _________________


INVENTORY # 2: TOTAL HOUSEHOLD WATER USE

Find your water bills and read the amount of water used which is usually given in thousands of gallons. The bill is usually for a 3 month period. Try to find the last four bills for a year period of time. If you live in an apartment or dorm, try to obtain this information from family, friends, or relatives that live in a house or you may access data from a typical suburban house Utility Usage.

QUES. 3: From these bills, make the following calculations - show work:

VOLUME OF WATER IN GALLONS FOR A YEAR: _______________

VOLUME IN GALLONS FOR A DAY: _________________

WATER USAGE: The two common measures of water use are withdrawal and consumption.

Water is withdrawn when it is taken from a surface or groundwater source and taken to the place of use. Water is consumed when it is no longer available for reuse because of evaporation, contamination, seepage into the ground, or used by plants and animals. Although about 80% of the water withdrawn is used for irrigation and electric power cooling, only uses by irrigation lead to about half of the water consumed. About 23% of water withdrawn in the U.S. is consumed.

For Ques. 4 - 7 show work for calculations!!

QUES. 4a: Calculate the per capita water withdrawn per year (assume a population of 250 million). One trillion = 1 x 10 E12

Total Annual Water Withdrawn: 124 Trillion gallons of water per year withdrawn in U.S. - 1984

Graphic # 1:

ProfO Help! - Graphic to show example calculation
(Approx. ans. = 100,000 to 800,000)


QUES. 4b: Calculate the daily water withdrawn per person.
(Approx. ans. = 500 to 2000)


QUES. 5a: To find a more realistic number of gallons withdrawn per day per person, calculate 10% of the above answer (4b) which represents the public water withdrawn.

ProfO Help! - General Method to work with Percentages

QUES. 5b: Use the answer to Ques 4b to find the gallons of water per person per day that is withdrawn for irrigation (41%).



OBJECTIVES FOR THE LAB:

1. Carry out serial dilutions to help in the understanding the small units of concentration which describe pollution in the environment.
2. Understand the meaning of ppm, ppb, and ppt. as very small concentration units.
3. Appreciate the fact that a zero concentration of pollutant is impossible to attain.

INTRODUCTION:

The news media and various environmental groups call for an ever increasing effort to "eliminate" or attain a level of "zero" concentration for a variety of air, water, and food pollutants. Is this an attainable goal? In this laboratory you will investigate the properties of "pollutants" to try to find a "zero" level of concentration.

 

PART 1: RESIDENCE TIME OF A POLLUTANT (5 points)
(Application of the Scientific Method)

****All Data for Part 1 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.*****


An important question is, "How long does it take for a pollutant to be rinsed out of a water basin such as a pond, lake, or river?" If water in a basin is polluted, the time is takes for the fresh water to rinse out the pollutant may depend on two factors (flow rate and/or size of the basin) which you will discover in this procedure. The average time that a pollutant or a normal water molecule spends in the basin is called the residence time. Pollution of waters with long residence times is not easily reversed.

QUES. 6: How long does it take for a pollutant to be rinsed out of a water basin such as a pond, lake, or river?
State your hypotheses for the following:
Hypothesis on the effect of flow rate:


Hypothesis on the effect of size of basin:


PROCEDURE 1:

STOCK DYE SOLUTION AND REFERENCE DYE SOLUTIONS:


These solutions are to be used as "reference" dye concentrations for Proc. 1.
1. Make a food color "stock" dye solution (the food color simulates a pollutant) by mixing 20 drops (1 ml) of dye with 1 quart or 1 liter of water in a quart or liter jar. Mix the solution well.

2. Standard Reference Diluted Solutions : Dilute the "stock" dye solution in the following manner: Use clear drinking cups for all containers. Follow the mixing instructions in the following table. These solutions will help to estimate the concentrations in unknown dye color solutions used in Proc. II..

Table of Food Color Dye Concentrations in Reference Solutions

 Milliliters dye  Milliliters water   Percent Dye Concentration
 1 cup (240 ml)   0  100 (original solution)
 3/4 cup (180 ml)  1/4 cup (60 ml)  75 %
 1/2 cup (120 ml)  1/2 cup (120 ml)  50 %
 1/4 cup (60 ml)  3/4 cup (180 ml)   25 %
 1/8 cup (30 ml)  7/8 cup (210 ml)  12.5%




PROCEDURE 2: "EXPERIMENTS"
A. TEST VARIABLES OF FLOW RATES:

1. Variable # 1: Adjust the water flow from the water faucet in the sink to about 30 ml/sec., which is about 8 seconds to fill a cup. Once you have the correct flow rate, do not adjust it or turn it off until this part of the experiment is complete.

2.. Fill the a small glass jar (about 1-2 cups of volume) completely full the jar with the stock dye solution. Now set the small glass jar under the flowing tap water so that the stream falls into the center of the jar. Keep your eye on the second hand of a watch and every 10 seconds remove the jar from under the running water. Visually compare the jar containing the dye to the five standard reference solutions to estimate the intensity of the color as percent dye concentration. It is probably better to look at all of the containers from the side, rather than causally from the top. Record the percent dye concentration.

Then continue by putting the small jar back under the running water for another 10 seconds, remove the jar and again compare the color in the jar to the five standard reference solutions and record the percent dye concentration. If the color is between two percent concentrations, then estmate a value between the two. Continue in this manner.
ProfO Notes: Comparison to Reference Standards Graphic


*Finally, record the time it takes for all visible evidence of the dye to disappear.*

3. Continue the experiment using the SAME FLOW RATE with Variable # 2 Part B, to find the effect of the size of the container at constant flow rate.

B. TEST VARIABLE OF BASIN SIZE (constant flow rate):

4. Variable # 2: For a different size container, but the same flow rate as variable # 1: Repeat the above exercise using a larger jar (about 2-4 cups in volume), again filled completely to the top with stock dye solution before starting and the same flow rate as used for the previous container in variable # 1. Again estimate the percent concentrations of dye in the container every 10 seconds as was done for variable # 1.


C. TEST VARIABLE OF FLOW RATE (constant size container):

5. Variable # 3: For a different variation in flow rate - slow the flow down, adjust the flow rate to 15 ml/sec or 16 seconds to fill a cup. Use the same size container as was used for variable # 1. Again estimate the percent concentrations of dye in the container every 10 seconds as was done for variable # 1.

Fill in the Data Table and Record your estimates of percent dye concentration at EACH 10 second time interval (Variable #1 and #2 and # 3 ) Use data from clickable links below.

 Time in seconds Flow Rate 30 ml/sec. Flow Rate 30 ml/sec. Flow Rate 15 ml/sec. 
   150 ml beaker  250 ml beaker  150 ml beaker
  percent concentration percent concentration  percent concentration 

 10
 see graphic

 75
 see graphic

 20
 see graphic

 50
 see graphic

 30
 see graphic

 20
 see graphic

 40

 trace

 10
 see graphic

 50

 no color

 5
 see graphic

 60
 

 trace

 trace

 70
 

 no color

 trace

 80
 

 no color

 no color





QUES. 7: Draw conclusions from the data. Compare and contrast the residence time of the pollutant dye molecules with the two factors of flow rate and size of container. For each factor make reference to which set of data you are using and to some actual data and times. Then make a generalization statement for each factor, and finally state whether the data suppports your hypothesis in Ques. 6.

7a. influence of the flow rate.

7b. and the size of the basin on the residence time.



PART 2: SERIAL DILUTIONS (5 points)

****At home collection of lab data****

 

Concentration units used in the environmental field are: ppm = part per million; ppb = part per billion; and ppt = part per trillion. One ppm is the same as one milligram of solid dissolved into 1000 grams of water (1000 g water = 1,000,000 milligrams).

Procedure:

1. Measure 2.5 teaspoons (10 ml) of tap water into a small cup. Use the eye dropper or food color dye bottle to measure 20 drops (1 ml) of dye and add to the water in the cup.

2. Read and understand the method to calculate the concentration of dye in this first solution. 10 ml water is the same as 10 grams of water; 20 drops (1 ml) dye = 1 g = 1000 mg. Now do a ratio problem; if there are 1000 mg of dye in 10 g water, how many milligrams are in 1000 g water.

1000 mg / 10 g equals "x" mg / 1000 g

solving for "x": 1000 x 1000 divide by 10 = 100,000 mg per 1000 g water, therefore 100,000 ppm dye

3. Save the pure solution of food color dye (100,000 ppm) already in the first cup (cup # 1).

4. Use a teaspoon to measure one teaspoon of pure tap water into 11 more small cups and label them cup # 2, 3, etc. through # 12.

5. Serial Dilution: To make the serial dilution, take 4 drops of dye solution from cup # 1 and put it into cup # 2. This now gives a total volume of 40 drops. You actually took 1/10 th out of # 1 and diluted it by 40 drops. So what is 1/10 th of 100,000 ppm? This now equals 10,000 ppm. Each dilution that we will be making is 1/10 th of the previous one.


6. Carefully rinse the eye dropper before continuing. Continue in the same manner for the rest of the cups. For the next serial dilution, take 4 drops from cup # 2 and put them in cup # 3. Be sure to mix well before going to the next one; then take 4 drops from # 3 and put them into # 4. Continue in a similar fashion. Fill in the table of the concentrations in ppm for each cup which follows.

7. Record the appearance in colors in the cups.

Fill in the TABLE OF CONCENTRATIONS FOR A SERIAL DILUTION in the ppm column.

 CUP NO.  Concentration in ppm  parts per billion  parts per trillion
 1

 100,000

 100,000,000

 100,000,000,000

 2

 10,000

 10,000,000

 10,000,000,000

 3  

 1,000,000

 1,000,000,000

 4  

 100,000

 100,000,000

 5  

 10,000

 10,000,000

 6  

 1,000

 1,000,000

 7  

 100

 100,000

 8  

 10

 10,000

 9  

 1

 1,000

 10  

 0.1

 100

 11  

 0.01

 10

 12  

 0.001

 1





QUES. 8: In which cup is the color no longer observable?__________________
What is the concentration of the dye in this cup?_____________ This represents the detection limit for dye using this visual method of detection.

QUES. 9a: Just because you can longer observe a color for the test, does this mean there is no more dye in that solution? Explain. Even a 1 part per trillion dilution contains 10,000,000,000 (10 trillion) dye molecules.

QUES. 9b: How many more dilutions would have to be made before there are NO molecules of dye present? (Not looking for an exact answer, but an understanding of the concept.)

HOW MUCH IS A PART PER BILLION? - Just some examples!!!
1 oz. salt in 32 tons potato chips = 1 part per million
1 pinch of salt in 10 tons of potato chips = 1 part per billion
1 drop vermouth in 80 fifths of gin = 1 part per million
1 drop vermouth in 500 barrels of gin = 1 part per billion

Even a very tiny concentration can add up to a sizable total amount of material when contained in a large sample. For example, consider the amount of material at the 1 part per billion level that is in the amount of water used by Los Angeles (3,000,000 acre-feet per year).

Enough lead to cast 1,000,000 bullets.
Enough mercury to fill 4,000,000 thermometers.
Enough phenols to produce 250,000 bottles of Lysol.
Enough herbicide to kill the dandelions in 100,000 lawns.



Two concepts which are related but often misunderstood are "Zero Pollution" and "Zero Discharge of Pollutants".

ZERO POLLUTION: A GOAL FOR THE 21ST CENTURY

Define and explain both of these concepts and then discuss whether either one is actually achievable from a practical and scientific stand point as in a) and b) below.

QUES. 10: Define zero pollution. The first term might be used in connection with cleaning up a polluted lake or pond - is it possible to get to a "zero pollution level? If a lake or pond contains some type of pollution, is it possible to clean the lake up to the point of having "zero pollution"?

QUES. 11: Define zero discharge of pollutants. The second term is often used in connection with the regulation of water out flow from a manufacturing plant - is it possible to achieve a "zero discharge of a pollutant"? Is it possible that the plant can treat all of the wastes so effectively that no pollutants are discharged? Or another way of thinking about this is whether all of the materials and by products are are so effectively recycled that no wastes need be discharged from the plant.