real world: calcium in milk
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DESCRIPTIONReal 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. - PowerPoint PPT Presentation
Real World: Calcium in Milk
Real World: Calcium in MilkBy: Chealsa Mooney and Christina RobinsonTo 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.PurposeProcedure OneCalmagite IndicatorWeighed out EDTA, dissolved in 1000mL. Resulted in 0.0361M EDTA solutionCreated ammonia bufferIn 250mL Erlenmeyer flask put 50mL of milk, 3mL ammonia buffer and small amount of calmagite indicator.Titrated with EDTA solution.Titration set up withCalmagite Indicator:Procedure TwoPatton-ReederUsed 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 ProcedureIn 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.DataTypes of milkPercentage of Calcium1% milk 60%2% milk 30%Nonfat skim milk 25%Lactose milk 50%Skim milk 45%DataCalmagite IndicatorEx: Soy milk
Aver: 0.02082gmL of EDTACa2+ conc. (g)Trial 116.8mL0.02327gTrial 215.2mL0.02105gTrial 313.1mL0.01814gCalmagite indicator color change:DataPatton-Reeder IndicatorEx: Soy milk
Aver: 0.02267gmL of EDTACa2+ conc. (g)Trial 119.3mL0.02673gTrial 213.3mL0.01842gTrial 316.5mL0.02285gPatton-Reeder indicator color change:DataSpikeEx: Soy milk
spikewithout spikeTrial 118.4mL17.3mLTrial 218.8mL17.9mLTrial 318.05mL17.1mLCalculationsEX: 1% milkCa2+ concentration in milkL EDTA x M EDTA x 1mol Ca 2+ x molar mass Ca 2+ 1mol EDTA0.0771 L x 0.0361 M x 1mol Ca 2+ x 40.078 g/mol Ca 2+ =0.11155 1mol EDTAGrams of Calcium per servinggrams Ca 2+ x volvol sample serving0.11155 g x 240mL = 0.53544 g50mL serving servingCalculations cont.Grams of Calcium per serving based on 2,000 calorie dietmg Ca 2+ (needed daily) x 1 g x %Ca 2+ in milk 1000 mg11oo mg x 1 g x 60% = 0.66g Ca 2+ 1000mg
Percent DifferenceActual - Experimental x 100%Actual0.66 - 0.5354 x 100% = 18.9%0.66Results: Percent DifferenceTypes:CalmagitePatton Reeder1% milk18.6%26.1%2% milk36.9%12.8%Nonfat skim milk102.4%64.4%Lactose milk7.68%46.2%Soy milk79.8%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)ReferencesDetermination 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.