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Real World: Calcium in Milk

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.

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Real World: Calcium in Milk

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

  2. 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.

  3. 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.

  4. Titration set up with Calmagite Indicator:

  5. 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.

  6. 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. • Titrated with EDTA solution.

  7. Data Types of milkPercentage of Calcium • 1% milk 60% • 2% milk 30% • Nonfat skim milk 25% • Lactose milk 50% • Skim milk 45%

  8. Data Calmagite Indicator Ex: Soy milk Aver: 0.02082g

  9. Calmagite indicator color change:

  10. Data Patton-Reeder Indicator Ex: Soy milk Aver: 0.02267g

  11. Patton-Reeder indicator color change:

  12. Data Spike Ex: Soy milk

  13. Calculations EX: 1% milk • Ca2+ concentration in milk L EDTA x M EDTA x1mol Ca 2+ xmolar mass Ca 2+ 1mol EDTA 0.0771 L x 0.0361 M x1mol Ca 2+ x40.078 g/mol Ca 2+ =0.11155 1mol EDTA • Grams of Calcium per serving grams Ca 2+ x vol vol sample serving 0.11155 g x 240mL = 0.53544 g 50mL serving serving

  14. 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

  15. Results: Percent Difference

  16. 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

  17. 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)

  18. 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/documents/calcium.pdf •Harris, Daniel C. Quantitative Chemical Analysis, 8th ed.; W.H. Freeman and Company: New York, 2010, page 240.

  19. Questions ?

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