One characteristic of blood that we rarely give a thought to is its pH. The pH of blood must be held remarkably constant, varying only by a few hundredths of a pH unit from 7.36 to 7.40. Blood pH is kept constant primarily through the buffering action of the bicarbonate ion, HCO3-, and dissolved carbon dioxide, commonly represented as H2CO3. The second ionization is negligible in blood so that H2CO3 can be treated as a monoprotic acid. A) If the Ka1 for H2CO3 is 4.2 * 10-7, what ratio of HCO3- to H2CO3 is necessary to produce a buffer of pH 7.40? B) What is the pH of a buffer that is 1.0 M NaHCO3 and 1.0 M H2CO3? C) If you have 1.00 L of the buffer described above (1.0 M NaHCO3 and 1.0 M H2CO3) and 10.0 mL of 0.100 M HCl is added to it, what is the new pH? D) Just to prove that the buffer helps minimize changes in pH, calculate the pH of a solution prepared by adding 10.0 mL of 0.1 M HCl to 1.00 L of pure water.
10. One characteristic of blood that we rarely give a thought to is its pH. The pH of blood must be held remarkably constant, varying only by a few hundredths of a pH unit from 7.36 to 7.40. Blood pH is kept constant primarily through the buffering action of the bicarbonate ion, HCO3-, and dissolved carbon dioxide, commonly represented as H2CO3. The second ionization is negligible in blood so that H2CO3 can be treated as a monoprotic acid.
A) If the Ka1 for H2CO3 is 4.2 * 10-7, what ratio of HCO3- to H2CO3 is necessary to produce a buffer of pH 7.40?
B) What is the pH of a buffer that is 1.0 M NaHCO3 and 1.0 M H2CO3?
C) If you have 1.00 L of the buffer described above (1.0 M NaHCO3 and 1.0 M H2CO3) and 10.0 mL of 0.100 M HCl is added to it, what is the new pH?
D) Just to prove that the buffer helps minimize changes in pH, calculate the pH of a solution prepared by adding 10.0 mL of 0.1 M HCl to 1.00 L of pure water.
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