Blood Buffer Lab

Topics: PH, Acid, Acid dissociation constant Pages: 2 (580 words) Published: March 18, 2012
The human blood buffer response to increased amounts of acids and bases was determined by titration of a 25.00 mL sample of H2PO4 buffer solution with 0.1 M HCl and 0.1 M NaOH. The volume of 0.1 M HCl is about double of the amount 0.1 M NaOH used to lower/raise the pH of a blood buffer.

In this experiment, HCl (a strong acid) and NaOH (a strong base) are used as examples of strong acids/bases, and the titration with H2PO4 shows the effect on a buffer solution. The assumption was the addition of large amounts of HCl will lower the pH, while the addition of large amounts of NaOH will increase the pH, while small amounts of either strong acid or base will not affect blood pH because of the buffer in blood.

Human blood has a natural buffer that can withstand a certain amount of acidosis or alkalosis before the pH drops drastically. Researchers have discovered that long periods of physical activity can cause sudden drops in pH of blood (acidosis) but will gradually return to its original state (Wood et al. 1976), which shows the human blood buffer at work.

The procedure is the same as in my Experimental Design Form.

17.033799 mL of HCl was needed to titrate a 25.00 mL sample of H2PO4 to lower the pH from 7.45 to 6.45, while 8.989089 mL of NaOH was needed to titrate a 25.00 mL sample of H2PO4 to raise the pH from 7.45 to 8.45. We determined that there was 0.034966 mL per drop by taking a 150 mL beaker and adding about 90 mL of H2PO4 and weighing by differences. We then let 100 drops drip through and divided the grams by number of drops to get mL per drop. The drop counter was used for the titration of HCl (which took 487 drops) and NaOH (257 drops) and multiplied 0.032977 mL/drop with the number of drops to get the total volume used for each solution.

The results of the experiment make sense in relation to the hypothesis, because the addition of HCl did decrease the pH and the addition of NaOH did increase the pH. A possible source of error is...
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