THE CONCENTRATION OF CALCIUM IN BONES

Pat Benecewicz & Nathan Tompkins

Why we are doing this?* Compare concentrations of calcium from species to species.*Species:• Cow• Pig• Deer

* The two methods will be a whole bone soaking and a ground-up bone soaking both in vinegar.

Proposed Procedure1. 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.

ResultsStandardizatio

n Of EDTA First

Trial mL EDTA [EDTA] Average [ ] Standard Dev.1 13.09 .00916

.00870 .0009172 15.70 .007643 12.91 .00929

Masses:Bones (Type) Mass:Deer (Whole

Bone) 108.5450

Lamb (Whole Bone) 76.4206

Hog (Whole Bone) 292.5120

Deer (Ground Up) 4.9180

Lamb (Ground Up) 5.0013

Hog (Ground Up) 5.0097

Results (Cont.)Whole Bone Titration

Deer Lamb HogTrail 1 39.69 45.90 20.00Trail 2 39.89 45.90 17.75Trail 3 40.04 45.91 17.89

% Ca2+ (Trial 1) .012745 .020934 .002383% Ca2+ (Trial 2) .012809 .020934 .002115% Ca2+ (Trial 3) .012857 .020939 .002132Average % Ca2+ .012804 .020936 .002210Standard Dev. .0000564 .00000263 .000150

Results (Cont.)Standardizat

ion Of EDTA Second

Trail mL EDTA [EDTA] Average Standard Dev.

1 12.21 .02455.02458 .000023092 12.19 .02459

3 12.19 .02459

Results (Cont.)Ground Bone Titration

Deer Lamb HogTrial 1 44.79 55.79 57.09Trail 2 41.59 56.55 53.62Trail 3 42.30 57.40 55.35

% Ca2+ (Trial 1) .008971 .010988 .011225% Ca2+ (Trial 2) .008330 .011137 .010543% Ca2+ (Trial 3) .008472 .011305 .010883Average % Ca2+ .008591 .011143 .010833Standard Dev. .000337 .000159 .000341

Sample Calculations

Discussion The purpose of this lab was to extract

calcium from bones using vinegar (acetic acid).

Acetic acid breaks apart CaCO3 in the bones leaving the Ca2+ ion floating in the vinegar and producing CO2 .

This was observed when bubbles were forming around the bones when they were in the vinegar.

Discussion Cont. We formed a hypothesis that the hog

would have the most calcium in it while the lamb would have the least amount of calcium in it.

Our data proves otherwise. In both methods, the lamb had the highest percent of calcium.

Grinding up the bones did not help extract more calcium than the whole bone soak.

Discussion Cont. A precipitate formed when we added the

buffer to the vinegar. We found out that this white precipitate was Ca(OH)2. Proving that we had our target ion in the vinegar solution.

The precipitate disappeared once we reach the endpoint.

ANY QUESTIONS?