Real World: Calcium in Milk By: Chealsa Mooney and Christina Robinson.
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Transcript of Real World: Calcium in Milk By: Chealsa Mooney and Christina Robinson.
Real World: Calcium in Milk
By: Chealsa Mooney and Christina Robinson
• 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.
Purpose
Procedure One
Calmagite Indicator1.Weighed out EDTA, dissolved in
1000mL. Resulted in 0.0361M EDTA solution
2.Created ammonia buffer3. In 250mL Erlenmeyer flask put 50mL
of milk, 3mL ammonia buffer and small amount of calmagite indicator.
4.Titrated with EDTA solution.
Titration set up withCalmagite Indicator:
Procedure TwoPatton-Reeder1.Used same solution of EDTA.2. In 250mL Erlenmeyer flask put 10mL
of milk, 40mL distilled water, and 4mL of 8M NaOH.
3.Allowed solution to sit for 5 minutes for precipitate to form.
4.Added 0.05g of Patton-Reeder indicator when precipitate formed.
5.Titrated with EDTA solution.
Spike Procedure
1. In 250mL Erlenmeyer flask put 10mL of milk, 3mL ammonia buffer, 1mL spike and small amount of calmagite indicator.
2.Titrated with EDTA solution.3.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.
4.Titrated with EDTA solution.
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 IndicatorEx: 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 IndicatorEx: 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
SpikeEx: Soy milk
spike without spike
Trial 1 18.4mL 17.3mL
Trial 2 18.8mL 17.9mL
Trial 3 18.05mL 17.1mL
CalculationsEX: 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
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
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)
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.
Questions ?