Calcium Carbonate Titration
Ashwin Rao
Ms. Farrow
SCH 3U1
Calcium Carbonate Titration
Ashwin Rao
Ms. Farrow
SCH 3U1

Purpose
To measure the percent by mass of CaCO3 in an eggshell.
Safety Precautions * Wear safety glasses. * Tie back long hair. * Roll up sleeves and/or do not wear baggy or loose clothing. * If any glass is broken, do not pick it up with bare hands. * Sweep the glass into a dustpan and place in broken glass bucket. * Be careful when pouring acid or base. * If any is spilled on hands, wash thoroughly with soap and water.
Materials
* * Safety glasses * Tap water * Masking tape * Precision scale * Pen/pencil & paper * Egg * Buret * Buret clamp * Retort stand * 3 Erlenmeyer flasks * 10 mL graduated cylinder * Wash bottle * Distilled water * 3 Beakers * 250 mL beaker for base * 100 mL beaker for acid * 500 mL beaker for waste * Ethanol * Phenolphthalein * Sodium Hydroxide (NaOH) * Hydrochloric Acid (HCl) * Hot plate * Hot hands * Scoopula *

Break the egg, and get rid of the yolk and egg whites into a large beaker.
Break the egg, and get rid of the yolk and egg whites into a large beaker.
Wash the shell with tap water and peel off the membranes with your fingers.
Wash the shell with tap water and peel off the membranes with your fingers.
Pat dry with paper towel and allow the shells to dry for a few days.
Pat dry with paper towel and allow the shells to dry for a few days.
Crush the shells to a fine powder with a mortar and pestle.
Crush the shells to a fine powder with a mortar and pestle.
Procedure—Prelab
Procedure—Prelab

Weigh between 0.450g and 0.550g of dried shell into each Erlenmeyer flask.
Weigh between 0.450g and 0.550g of dried shell into each Erlenmeyer flask.
Add many drops of ethanol to act as a wetting agent and help the HCl dissolve the CaCO3.
Add many drops of ethanol to act as a wetting agent and help the HCl dissolve the CaCO3.
Pour 10.0 mL of 1.0 M HCl into a graduated cylinder and then in each flask.
Pour 10.0 mL of 1.0 M HCl into a graduated cylinder and then in each flask.
Swirl the acid around to wet all the eggshell.
Swirl the acid around to wet all the eggshell.
Heat the solutions in a hotplate until they begin to boil. Allow to cool and rinse sides with water from wash bottle
Heat the solutions in a hotplate until they begin to boil. Allow to cool and rinse sides with water from wash bottle
Add 3-4 drops of phenolphthalein to each flask. The solution should remain clear because it is acidic.
Add 3-4 drops of phenolphthalein to each flask. The solution should remain clear because it is acidic.
Procedure—Setup
Procedure—Setup

Procedure—Titration
Procedure—Titration
Rinse out buret with water, then with NaOH.
Rinse out buret with water, then with NaOH.
Fill the buret with NaOH, and slowly drip it into HCl till the first pink colour that remains pink for 30 seconds appears.
Fill the buret with NaOH, and slowly drip it into HCl till the first pink colour that remains pink for 30 seconds appears.
Repeat for the other two samples.
Repeat for the other two samples.
Calculate the percent CaCO3 in each sample.
Calculate the percent CaCO3 in each sample.
Wash all equipment used with hot soapy water and a test tube brush.
Wash all equipment used with hot soapy water and a test tube brush.

Observations
Titration of NaOH with solid acid standard | Rough | Trial #1 | Trial #2 | Trial #3 | Volume Oxalic Acid | 25 mL | 25 mL | 25 mL | 25 mL | Final Volume Base | 24.1 mL | 24.2 mL | 24.0 mL | 24.2 mL | Initial Volume Base | 0 mL | 0 mL | 0 mL | 0 mL | Volume Base Used | 24.1 mL | 24.2 mL | 24.0 mL | 24.2 mL |

Titration of NaOH with HCl Mass of Eggshell | 0.45 g | 0.50 g | 0.55 g | Volume HCl | 10 mL | 10 mL | 10 mL | Final Volume NaOH | 30.8 mL | 19.5 mL | 37.0 mL | Initial Volume NaOH | 0 mL | 0 mL | 19.5 mL | Volume NaOH Used | 30.8 mL | 19.5 mL | 17.5 mL |

Calculations
See attached page.

Analysis 1. The eggshells had to be dried completely to get the best results with the titrations. The lack of moisture in the shells also makes for a more accurate mass because there is no extra water-weight. Eggshells are a good source of calcium, but eating raw eggshells can lead to food poisoning due to salmonella or other bacterial contamination (Smith, 2013, “Eggshell as a Source of Calcium”).

2. There are many sources of error that could have altered the outcome of this experiment. * When removing the membrane from the inside of the shell, all of it might not have been removed. This can alter the outcome of the experiment because it adds extra mass. It can also change the chemical reaction that takes place between the acid and base. * The eggshell might not have dried completely which can add extra mass to the shell. * Some of the equipment used such as beakers and Erlenmeyer flasks might not have been cleaned thoroughly enough before starting the experiment. This can add unwanted chemicals and reactants to the reaction thus changing the products. This can remove or add mass to the precipitate formed.

3. My highest percent yield was 80.0% which was when I produced 0.40 g CaCO3 out of 0.50 g. My results were fairly consistent as I all three of my tests produced within 74-80% CaCO3. But, during my titrations, the volume of NaOH that I used were very different between the tests. I learned that producing calcium carbonate from eggshells is not the most efficient way because in the past lab, we were able to produce more than 2.00 g with a much shorter and faster procedure.

4.
DDT
http://upload.wikimedia.org/wikipedia/commons/4/42/DDT_chemical_structure_highres.png http://upload.wikimedia.org/wikipedia/commons/4/42/DDT_chemical_structure_highres.png DDT was one of the first widely used pesticide. It was greatly promoted following WWII, but even 40 years after banning it in the US, its long-lasting effects are felt. The pesticide is a health hazard for all living things. Bald eagle population severely declined because of the thinning off eggshells from DDT. After it was banned, bald eagles made a dramatic recovery. There are also many human health harms including breast and other cancers, male infertility, and miscarriages. The only legal use of DDT left is controlling malaria-carrying mosquitoes. Indoor spraying is being utilised but is rarely the most effective choice. (“The DDT Story,” n.d.)
DDT is biomagnified through the food chain. It starts with microorganisms such as plankton, which are eaten by fish, which are then eaten by birds. Microorganisms and invertebrates can accumulate a lot of the DDT in their bodies, and the next predator in the food chain eats in the DDT-affected prey in excess. The amount of DDT multiplies rapidly as it eventually gets to birds. (“Effects of DDT,” n.d.)
DDT can change into different forms than the original. These interfere with certain reproductive enzymes in birds. Certain enzymes affect the amount of calcium deposited in eggshells. DDE, a form of DDT probably gets in the way of these enzymes. Therefore eggshells have less calcium, making them easier to break. (“Eggshell Thinning,” n.d.)
The thinning of eggshells severely decreases the population of birds too rapidly, causing a problem in the food chain as a predator and prey will be taken out before other animals can adapt.
PCB’s
http://upload.wikimedia.org/wikipedia/commons/thumb/6/64/PCB_structure_general.svg/380px-PCB_structure_general.svg.png http://upload.wikimedia.org/wikipedia/commons/thumb/6/64/PCB_structure_general.svg/380px-PCB_structure_general.svg.png PCB’s are found in the environment, which ends up in foods. This means everyone is exposed to low levels of PCB’s. In low concentrations, PCBs seem to not affect human health, but it can accumulate remain there for years. PCB stands for Polychlorinated Biphenyls which refers to any one, or any combination of 209 specific chemicals that are similar in structure. They are long-lasting because they do not break down easily on their own, and are hard to destroy. First manufactured in 1929, PCBs were used as ingredients in industrial materials such as sealing and caulking compounds, cutting oils, inks and paint additives, and coolants and lubricants for certain electrical equipment (i.e. transformers and capacitors). (“PCBs” 2001, November)
Trace levels of PCBs are found in the environment (air and water) around the world. Nowadays, contamination is caused by long-range transport of PCBs by global air-currents. PCBs accumulate in the cells of animals, meaning the top of the food chain is most affected (biomagnification). With exposure to much more than the levels normally found in the environment, health effects include chloracne, swelling of the upper eyelids, discolouring of the nails and skin, numbness in the arms and legs, weakness, muscle spasms, chronic bronchitis, problems related to the nervous system and increased incident of cancer, specifically liver and kidney. Eating large amounts of certain sports fish, wild game and marine mammals increases the risk for higher exposures. But, salmon from a commercial food supply does not pose a health risk to consumers. (“PCBs” 2001, November)
There are many impacts that PCBs have on birds, one being reproductive. Embryo mortality is occurring because of the decrease in hatchability of eggs. Therefore, there are a fewer amount of eggs produced. This is because the egg shell is being thinned by PCBs. (Friend & Franson (n.d.). “Polychlorinated Biphenyls”)
Dioxin
http://cerch.org/wp-content/uploads/2010/09/Dioxin-chemical-structure.jpg http://cerch.org/wp-content/uploads/2010/09/Dioxin-chemical-structure.jpg Dioxin is an unwanted contaminant in the very common herbicides 2,4,D and 2,4,5 T. It is a result of a side reaction and is very hard to remove. It’s also a biproduct of other industrial processes like the paper industry. Dioxin lingers in the environment because it is extremely hydrophobic; it does not wash away with rain. Once dioxin is ingested by an animal, it accumulates in fat tissue and not flushed out, so it ca become relatively concentrated. (“Molecule of the Day: Dioxin” n.d.)
It is the most cancer causing substances ever tested in guinea pigs. After much research, it was found that it doesn’t cause cancer in humans like it does in guinea pigs. Dioxin is now thought to be an “environmental estrogen” as estrogens are hydrophobic and about the same size as dioxin. The dioxin molecule binds to steroid receptors called the Ah receptors. They normally bind steroids and goes to the cell nucleus and binds to DNA and turns on certain genes. The activated genes control complex functions, and if they are always activated by dioxin, it causes problems. Dioxin does not bind human Ah receptors as well as guinea pigs’ so it is not as much of a danger to us. But, it is still toxic and not safe to be exposed in large quantity. (“Molecule of the Day: Dioxin” n.d.)
Dioxin can cause many problems, but it does not affect the thickness of eggshells.
Thinning of Eggshells
The thinning of eggshells is a major environmental concern because it can severely decrease the population of birds, of prey specifically. When there is less calcium in the eggshell, it makes the egg thinner and more fragile. The eggshell is more likely to crack and break. When this happens in excess, the whole population could potentially disappear. This can remove a big piece from the food chain, leaving an excess of one species and an absence of another.

Conclusion
In conclusion, I learned that eggshells are an excellent source of calcium. However, chemicals such as DDT and PCBs can alter the amount of calcium in the shell, therefore making them thinner. These chemicals are bad because they can greatly affect populations of species. When eggshells are mixed with hydrochloric acid and then neutralized with sodium hydroxide, it extracts the calcium in the eggshell. My experimental findings were fairly similar to other students’.
Sources of error * When removing the membrane from the inside of the shell, all of it might not have been removed. This can alter the outcome of the experiment because it adds extra mass. It can also change the chemical reaction that takes place between the acid and base. * The eggshell might not have dried completely which can add extra mass to the shell. * Some of the equipment used such as beakers and Erlenmeyer flasks might not have been cleaned thoroughly enough before starting the experiment. This can add unwanted chemicals and reactants to the reaction thus changing the products. This can remove or add mass to the precipitate formed.

References
The DDT Story. (n.d.). Retrieved June 2, 2014, from http://www.panna.org/issues/persistent-poisons/the-ddt-story
Effects of DDT. (n.d.). Retrieved June 2, 2014, from http://people.chem.duke.edu/~jds/cruise_chem/pest/effects.html
Eggshell Thinning. (n.d.). Retrieved June 2, 2014, from http://people.chem.duke.edu/~jds/cruise_chem/pest/eggs.html
Friend, M., & Franson, J. C. (n.d.). Polychlorinated Biphenyls. Retrieved June 2, 2014, from http://www.nwhc.usgs.gov/publications/field_manual/chapter_41.pdf
Molecule of the Day: Dioxin. (n.d.). Retrieved June 2, 2014, from http://iverson.cm.utexas.edu/courses/old/310N/spring2008/MOTD%20Fl05/MOTDfl02%20copy/MOTDDioxin.html
PCBs. (2001, November). Retrieved June 2, 2014, from http://www.hc-sc.gc.ca/hl-vs/iyh-vsv/environ/pcb-bpc-eng.php
Smith, J. (2013, November 03). Eggshell as a Source of Calcium. Retrieved June 1, 2014, from http://www.livestrong.com/article/490605-eggshell-calcium-as-a-source-of-calcium/