· Purpose: The purpose of this lab is to compare the corrosive effects of non- titrated Sprite with titrated sprite, using two bases to lessen the pH to see if the level of pH affects the corroding power; the concentration of Sprite in each of the titrated solution will also be discovered.
· Title: Corrosive effects of Coke after titration
· Group Members: John Miller, William Aldrich, Chris Eisenhart
· Background Information:
o Sprite, like any other soft drink, has its acidic nature. It contains the common citric acid, and because of the carbonated water, it also contains carbonic acid. Along with the ingredients that make the beverage acidic, there is also sugar, flavorings, preservative (E211) and an acidity regulator (E331). The preservative is also known as sodium benzoate and the acidity regulator is a type of sodium citrate. This acidity regulator controls the pH of the drink so it is not harmful to the human body. It also adds some taste. Sprite has a pH of about 4 (3.91-1.08) and although it is not very acidic, it does have acidic capabilities. Titration is an analytical method in which a standard solution is used to determine the concentration of an unknown solution. An indicator is placed into the acidic solution that is being tested (in this case, the Sprite) and a base is poured into it, drop by drop. When the ions in the base and the acid equal out, the indicator color will change and the solution will have reached its equivalence point. This equivalence point will be closer to neutral than the acid is by itself and should have less corrosive abilities.
o Titration equation- Acid ( M*V*N) = Base (M*V*N)
§ N= number of hydrogen moles in the base and the acid ( for example H2SO4, Sulfuric Acid has 2 hydrogen moles)
§ M= Molarity or concentration for the base and the acid
§ V= volume or amount of base and acid
§ Bromothymol Blue will be the indicator used to change the color of the sprite .This indicator will start as yellow, and it will change to blue once it reaches a pH range of 6.0- 7.6 . Sprite has a starting pH of 3.9 so once the pH is reduced to the mention range it will change color.
§ In this lab, Sodium Hydroxide(NaOH), and Ammonium Hydroxide (NH4OH) will be used to titrate the Coca-Cola decreasing the pH of the soda, and hopefully the corroding power.
o § Sodium Hydroxide severely irritates the respiratory system, and it causes corroding and leaves severe tissue damage in the digestive tract. Also, this base will burn skin and leave burns and scars with great damage: the base will cause the same damage to the eyes.
o Ammonium Hydroxide causes irritation to respiratory tract in low concentration but can be fatal in high concentrations. If ingested ammonium hydroxide is toxic and may cause death. Nonetheless, this base only causes irritations.
· Hypothesis: When the cheese is placed in the three solutions, it will dissolve least in the Ammonium Hydroxide by at least two grams.
· Safety Information: Wear goggles, gloves and an apron. Handle all the chemicals with care and avoid contact with any extremities and/ or eyes. Make sure to clean any messes thoroughly that may arise.
· Materials:
o 50 mL Buret
o 6 Ring Stands
o Buret Clamp
o 2 12 oz. cans of Sprite
o 100 mL1.0M NaOH
o 120 mL 1.0M NH4OH
o Five funnels
o A few drops of Bromothyml Blue
o Water
o 3 pieces of filter paper
o Filter Clamp
o 3 250mL Erlenmeyer Flasks
o Discard Beaker
o 3 Similar Pieces of Cheese
o Scale
o 3 size 6 rubber stoppers
o Five pieces of filter paper
· Preliminary Calculations:
o C6H7O8 = NaOH
§ 2 x 50 x M = 1 x 1 x V
§ 100M = V
o C6H7O8 = NH4OH
§ 2 x 50 x M = 1 x 1 x V
§ 100M = V
o Diluting equation for NH4OH
§ 6M NH4OH * (XmL) = 1M NH4OH * ( 120mL)
§ X = 20 mL of 6M NH4OH.
· Procedures:
1. Select a buret to use for the experiment. Rinse buret with water. Fill the pipet with a small portion of 1.0 M NaOH and then release into a discard beaker. Set up the titration equipment. Carefully attach the buret to the ring stand using a buret clamp. Obtain an Erlenmeyer flask.
2. Carefully transfer 50 mL of Sprite and add a few drops of Bromothyml Blue to the Erlenmeyer flask.
3. Carefully add 100 mL of 1.0 M NaOH to the buret.
4. Add base to this well, drop wise, with swirling, until a faint blue color is observed that remains for 30 seconds on standing. Record the amount of NaOH required to keep the color change.
5. Repeat this procedure using a new sample of Sprite with Bromothymol Blue added to it. Also, replace the 1.0M NaOH with 1.0M NH₄OH.
6. Check your data. Your first titration should be similar to your second titration. If they are not, you need to be able to account for the differences.
7. Fill a third flask with 50 mL of regular Sprite.
8. Cover all three solutions with a rubber stopper and left them sit over night.
8. Clean up the titration equipment.
9. Get a scale and zero it in, then measure the weight of the cheese ( before it has been dropped into the solution)
10. Drop a piece of cheese in each of the flasks at the same time and cover the flasks with stoppers again. Record any observations.
11. While the cheese dissolves, calculate the concentration of coke in the two titrated solutions.
12. Allow the cheese to dissolve overnight.
13. Weigh mass of the filter paper.
14. Set up filtration system, and then filter out the cheese
15. Make observations and weigh the cheese from each of the three solutions, subtract the weight of the filter paper without cheese from the mass of the filter paper with cheese in weight.
16. Finally, determine the weight of the cheese.
· Data/Observations:
Trial # / Drops of Bromothyml Blue / Volume of Sprite / Volume of NaOH1 / 5-10 / 50mL / 3.2 mL
Concentration of Citric Acid Titrated with NaOH- .032 M
100M=(3.2mL), M= 3.2/100 = .032 M
Trial # / Drops of Bromothyml Blue / Volume of Sprite / Volume NH4OH1 / 5-10 / 50mL / 6.5 mL
Concentration of Citric Acid Titrated with NH4OH- .065M
100M= (6.5mL), M = 6.5/100 = .065 M
Observations- Just Sprite-· Cheese floats and fizzing occurs around the edges of the cheese.( immediately after placing cheese in)
After Dissolving overnight-
· Clear liquid
· Half of the cheese is sunk
· Few cracks in cheese
· Very small particles
· Small bubbles on cheese.
· Cheese owned a dark Yellowish-orange color / Observations- Sprite titrated with NaOH-
· Cheese does not float and fizzing does not occur( immediately after placing cheese in)
After Dissolving overnight-
· Less particles are floating around
· Greenish, murky liquid
· Cheese is light yellow in the middle and fades to white on outer edges
Observations-
Sprite titrated with NH4OH-
· Cheese does not float and fizzing does not occur( immediately after putting cheese in)
After Dissolving overnight-
· Jade Green, murky liquid
· Cheese is light yellow in middle, fades to white on outer edges
· Parts of the cheese broke off
· Cracks in the cheese
Weight of cheese (in grams) / Before / After / Difference
Just Sprite / 4.281g / 2.684g / 1.597 g
Sprite with Sodium Hydroxide / 4.519g
Sprite with Ammonium Hydroxide / 5.028g
Work Cited
Carter, J. S. "PH Testing Results." Biology at Clermont College - University of Cincinnati. J. Stein Carter, 21 Sept. 2010. Web. 09 May 2011.
"E211 - Sodium Benzoate - Preservatives." Food Figures - Food Additives (E Numbers) Safety Information, Food Database, Nutrition Information, Health Information. Web. 09 May 2011.
"Food-Info.net : E-numbers : E331 Sodium Citrates." Food-Info. Food-Info, 5 Mar. 2011. Web. 09 May 2011.
“Safety Data for Ammonium Hydroxide.” www.msds.chem.ox.ac.uk. 29 March 2011. PTCL Safety. N.pag. Web. 9 May 2011.
“Safety Data for Sodium Hydroxide.” www.msds.chem.ox.ac.uk. 17 September 2011. PTCL Safety. N.pag. Web. 9 May 2011.
"Sprite : Ingredients : Nutrition : GDA - Coca-Cola GB." Home of Coca-Cola UK : Diet Coke : Coke Zero - Coca-Cola GB. The Coca-Cola Company, 2010. Web. 09 May 2011.