Real World: Calcium in Milk By: Chealsa Mooney and Christina Robinson

Purpose To determine how much calcium was in different types of milk and comparing them to their known values. Using two different types of indicators and comparing the results they produce.

Procedure One Calmagite Indicator Weighed out EDTA, dissolved in 1000mL. Resulted in 0.0361M EDTA solution Created ammonia buffer In 250mL Erlenmeyer flask put 50mL of milk, 3mL ammonia buffer and small amount of calmagite indicator. Titrated with EDTA solution.

Titration set up with Calmagite Indicator:

Procedure Two Patton-Reeder Used same solution of EDTA. In 250mL Erlenmeyer flask put 10mL of milk, 40mL distilled water, and 4mL of 8M NaOH. Allowed solution to sit for 5 minutes for precipitate to form. Added 0.05g of Patton-Reeder indicator when precipitate formed. Titrated with EDTA solution.

Spike Procedure In 250mL Erlenmeyer flask put 10mL of milk, 3mL ammonia buffer, 1mL spike and small amount of calmagite indicator. Titrated with EDTA solution. To test without the spike to see if it produced the same result we put in a 250mL Erlenmeyer flask 10mL of milk, 3mL ammonia buffer and small amount of calmagite indicator.

Data Types of milk Percentage of Calcium 1% milk 60% 2% milk 30% Nonfat skim milk 25% Lactose milk 50% Skim milk 45%

Data Calmagite Indicator Ex: Soy milk Aver: 0.02082g mL of EDTA Ca2+ conc. (g) Trial 1 16.8mL 0.02327g Trial 2 15.2mL 0.02105g Trial 3 13.1mL 0.01814g

Calmagite indicator color change:

Data Patton-Reeder Indicator Ex: Soy milk Aver: 0.02267g mL of EDTA Ca2+ conc. (g) Trial 1 19.3mL 0.02673g Trial 2 13.3mL 0.01842g Trial 3 16.5mL 0.02285g

Patton-Reeder indicator color change:

Data Spike Ex: Soy milk spike without spike Trial 1 18.4mL 17.3mL

Calculations EX: 1% milk Ca2+ concentration in milk L EDTA x M EDTA x 1mol Ca 2+ x molar mass Ca 2+ 1mol EDTA 0.0771 L x 0.0361 M x 1mol Ca 2+ x 40.078 g/mol Ca 2+ =0.11155 Grams of Calcium per serving grams Ca 2+ x vol vol sample serving 0.11155 g x 240mL = 0.53544 g 50mL serving serving

Calculations cont. Grams of Calcium per serving based on 2,000 calorie diet mg Ca 2+ (needed daily) x 1 g x %Ca 2+ in milk 1000 mg 11oo mg x 1 g x 60% = 0.66g Ca 2+ 1000mg Percent Difference Actual - Experimental x 100% Actual 0.66 - 0.5354 x 100% = 18.9% 0.66

Results: Percent Difference Types: Calmagite Patton Reeder 1% milk 18.6% 26.1% 2% milk 36.9% 12.8% Nonfat skim milk 102.4% 64.4% Lactose milk 7.68% 46.2% Soy milk 79.8% 16.8%

Conclusion - The calmagite indicator took a lot more EDTA to reach the endpoint -Overall, the Patton-Reeder indicator produced better results although the lowest percent difference came from the Lactose milk using the Calmagite indicator. (7.68% difference) -Calmagite indicator with the skim milk produced the highest percent difference (102%) -The spike test produced good results. It took about that same amount of EDTA to titrate samples with and without the CaCO3

Sources of error: - misreading the buret - Some trials might have needed to be titrated more (blue endpoint but then after a minute it would go back to purple) -not letting the milk sit long enough to let the magnesium oxide form. (that's what reacted with the indicator)

References Determination of Calcium Ion Concentration. College of Science. University of Canterbury, n.d. Web. 12 Dec. 2012. http://www.outreach.canterbury.ac.nz/chemistry/docume nts/calcium.pdf •Harris, Daniel C. Quantitative Chemical Analysis, 8th ed.; W.H. Freeman and Company: New York, 2010, page 240.

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