Real World Project: the concentration of calcium in bones
Purpose: This experiment will allow us to determine the concentration of calcium in different animal bones (hog,
lamb and deer) by use of an EDTA titration. One Method will have one whole bone form each animal specimen
soaking in vinegar, while the second method will have about 5 grams of ground bone from each animal specimen
soaking in 100mL of vinegar.
Procedure:
1. Soak the bones in boiling water to take the meat off just leaving the cartilage and bone.
2. Dry the bones overnight to remove any excess water off the bones.
3. Mass the femurs of each animal.
4. Put the femurs of each animal into a container and fill with vinegar to completely cover the bones. Let them
soak for a week.
5. Take the tibias of each animal and cut a 1 inch section from each bone.
6. Crush the bone using a mortor and pestle and mass 5 grams of bone from the ground bones.
7. Put each 5g portion in a 150mL beaker and add 100mL of vinegar. Let them soak for a week.
8. Make a .01M solution of EDTA using 1.8600g of EDTA in 500mL of DI water.
9. Make a .1M solution of CaCO3 using 1.000g of CaCO3 in 2M HCl. Make an ammonia buffer with 6M NH4OH and
adding 6M HCl until the pH is 10.00.
10. Standardize the EDTA solution with 3mL of the CaCO3, 5mL of ammonia buffer, and 4 drops of calmagite
indicator. Repeat two more times.
11. Remove the bones from the vinegar and allow the bones to dry. Record the volume of vinegar used for the
whole bones.
12. Take 5mL of the vinegar solution, 5mL of ammonia buffer, and 4 drops of calmagite and titrate to the blue
endpoint with the standardized EDTA.
13. Do this titration 3 times for each whole bone vinegar solution and 3 times for each ground up bone vinegar
solution.
14. Calculate the concentration of calcium in each vinegar solution.
Data:
Standardization
of EDTA: first
1.8605 g
Trail
Mass:
mL
EDTA
1
13.09
0.00916
2
15.7
0.00764
3
12.91
0.00929
Average
0.0087
Stand. dev
0.000917
M EDTA
Samples:
Deer Whole
Bone
Lamb Whole
Bone
Hog Whole Bone
Deer Ground
Bone
Lamb Ground
Bone
Hog Ground
Bone
Masses:
108.545
76.4206
292.512
4.918
5.0013
5.0097
Whole Bone
Titration:
Standardization
EDTA: second
Trail 1 (mL)
Trail 2 (mL)
Trail 3 (mL)
% Ca2+ (T1)
% Ca2+ (T2)
Deer
Lamb
Hog
39.69
45.9
20
39.89
45.9
17.75
40.04
45.91
17.89
0.012745 0.020934 0.002383
0.012809 0.020934 0.002115
% Ca2+ (T3)
0.012857 0.020939 0.002132
Average %Ca2+
Stand. dev
0.012804 0.020936
0.00221
5.64E-05
2.63E-06
0.00015
Deer
44.79
41.59
42.3
0.008971
0.00833
0.008472
0.008591
0.000337
Lamb
55.79
56.55
57.4
0.010988
0.011137
0.011305
0.011143
0.000159
Hog
57.09
53.62
55.35
0.011225
0.010543
0.010883
0.010883
0.000341
Trail
1
2
3
Mass:
mL
EDTA
M EDTA
12.21
12.19
12.19
Average
0.02455
0.02459
0.02459
0.02458
Stand. dev
2.31E-05
Ground Bone
Titration:
Trail 1 (mL)
Trail 2 (mL)
Trail 3 (mL)
% Ca2+ (T1)
% Ca2+ (T2)
% Ca2+ (T3)
Average % Ca2+
Stand. dev
Calculations:
Standardization of EDTA:
1.000𝑔 𝐶𝑎𝐶𝑂3 ×
1 𝑚𝑜𝑙 𝐶𝑎𝐶𝑂3
1
. 003 𝐿 1 𝑚𝑜𝑙 𝐸𝐷𝑇𝐴
1
×
×
×
×
= .00916𝑀 𝐸𝐷𝑇𝐴
100.0892𝑔 𝐶𝑎𝐶𝑂3 . 1 𝐿
1
1 𝑚𝑜𝑙 𝐶𝑎𝐶𝑂3 . 01358 𝐿
Percent Ca2+:
. 0369𝐿 𝐸𝐷𝑇𝐴 ×
. 00870𝑚𝑜𝑙 𝐸𝐷𝑇𝐴 1 𝑚𝑜𝑙 𝐶𝑎2+ 40.078𝑔 𝐶𝑎2+
1
×
×
×
= .012745%𝐶𝑎2+
1𝐿
1 𝑚𝑜𝑙 𝐸𝐷𝑇𝐴
1𝑚𝑜𝑙 𝐶𝑎2+
108.5450𝑔 𝑊ℎ𝑜𝑙𝑒 𝐵𝑜𝑛𝑒
Average Percent:
. 012745 + .012805 + .012857
= .12804%𝐶𝑎2+
3
1.8607 g
Conclusion:
Based on our results the Lamb had the greatest percentage of calcium. We had originally thought the
Hog would have the greatest amount of calcium because it had the greatest mass. The experiment went
well and gave us pretty consistent data to work with. It took many long morning s of preparation;
boiling, cutting, drying, and soaking, but in the end it all went well. There was some error with the fact it
was near impossible to remove all the meat and flesh from the bones and only leave the cartilage. A tiny
portion of unwanted matter was left on the bones, which may have stopped a small portion of calcium
form leaving the bones and absorbing into the vinegar.