<< Chapter < Page Chapter >> Page >

Blood is an important example of a buffered solution, with the principal acid and ion responsible for the buffering action being carbonic acid, H 2 CO 3 , and the bicarbonate ion, HCO 3 . When an excess of hydrogen ion enters the blood stream, it is removed primarily by the reaction:

H 3 O + ( a q ) + HCO 3 ( a q ) H 2 CO 3 ( a q ) + H 2 O ( l )

When an excess of the hydroxide ion is present, it is removed by the reaction:

OH ( a q ) + H 2 CO 3 ( a q ) HCO 3 ( a q ) + H 2 O ( l )

The pH of human blood thus remains very near 7.35, that is, slightly basic. Variations are usually less than 0.1 of a pH unit. A change of 0.4 of a pH unit is likely to be fatal.

The henderson-hasselbalch equation

The ionization-constant expression for a solution of a weak acid can be written as:

K a = [ H 3 O + ] [ A ] [HA]

Rearranging to solve for [H 3 O + ], we get:

[ H 3 O + ] = K a × [HA] [ A ]

Taking the negative logarithm of both sides of this equation, we arrive at:

−log [ H 3 O + ] = −log K a − log [ HA ] [ A ] ,

which can be written as

pH = p K a + log [ A ] [ HA ]

where p K a is the negative of the common logarithm of the ionization constant of the weak acid (p K a = −log K a ). This equation relates the pH, the ionization constant of a weak acid, and the concentrations of the weak acid and its salt in a buffered solution. Scientists often use this expression, called the Henderson-Hasselbalch equation    , to calculate the pH of buffer solutions. It is important to note that the “ x is small” assumption must be valid to use this equation.

Lawrence joseph henderson and karl albert hasselbalch

Lawrence Joseph Henderson (1878–1942) was an American physician, biochemist and physiologist, to name only a few of his many pursuits. He obtained a medical degree from Harvard and then spent 2 years studying in Strasbourg, then a part of Germany, before returning to take a lecturer position at Harvard. He eventually became a professor at Harvard and worked there his entire life. He discovered that the acid-base balance in human blood is regulated by a buffer system formed by the dissolved carbon dioxide in blood. He wrote an equation in 1908 to describe the carbonic acid-carbonate buffer system in blood. Henderson was broadly knowledgeable; in addition to his important research on the physiology of blood, he also wrote on the adaptations of organisms and their fit with their environments, on sociology and on university education. He also founded the Fatigue Laboratory, at the Harvard Business School, which examined human physiology with specific focus on work in industry, exercise, and nutrition.

In 1916, Karl Albert Hasselbalch (1874–1962), a Danish physician and chemist, shared authorship in a paper with Christian Bohr in 1904 that described the Bohr effect, which showed that the ability of hemoglobin in the blood to bind with oxygen was inversely related to the acidity of the blood and the concentration of carbon dioxide. The pH scale was introduced in 1909 by another Dane, Sørensen, and in 1912, Hasselbalch published measurements of the pH of blood. In 1916, Hasselbalch expressed Henderson’s equation in logarithmic terms, consistent with the logarithmic scale of pH, and thus the Henderson-Hasselbalch equation was born.

Questions & Answers

how does economics define me
clement Reply
what are the factors that determines the demand and supply
sillah
what are the importance of Economics
Betty Reply
tell me something very important about economics..
Fayaz Reply
how may I solve arithmetic mean ,,,all example
Cee Reply
what is agriculture
Itoe Reply
simple method of understanding cost concept
Oludare Reply
what is inflation
Christiana Reply
Inflation is a general increase in price levels
Zuko
is the action of inflating something
Abdifatah
inflation is the persistent increase in general price level of goods and services in an economy over a considerable period of time .
Tetteh
inflation is the general increase of a commodity in a particular period of time.
Turay
inflation is a general increase in price levels of commodities
shehu
what are the types of inflation?
Ebrima
inflation is the period of persistent rise in the general level of the price of goods services over time
Emmanuel
we have creeping inflation, demand pull inflation ,cost push inflation, and galloping inflation .
Emmanuel
how can a location of a firm create difference between producers
joy Reply
what is monetary policy
joy
hello
Abdifatah
is a monetary from policy that's authorized of country encharces
Abdifatah
What would you say about the the mobility of enterprise as a factor of production?
Cathryn Reply
how can I connect myself to this Ambrose platform
kanu Reply
I am good and you I am from sierra Leone and I am new her
kanu Reply
u are welcome bro, here is a good platform for you to be
Alie
That i know,thanks bro.
what the main definition of economic
Uhara Reply
the main definition is given by prof Lionel Robbins as a social science which studies human behavior between ends and scarce which have alternative uses
olajumoke
what covers macro economics.
Fayaz
Essay about Microsoft
Kwena Reply
what is economics
Julie Reply
what do you mean by means in economics
Julie
economic is the wealth of a country.
Moussa
monetary policy is refer to as being expansionary or contractionary.
Abdul
pls who can help me to explain money market and capital market
Au
money market is base on short term loan which is within one year period while capital market is long term loan more than one year...
Muhammad
money market is a market were short term loans are dealt with while capital market is a market were long term loans are traded
Ebrima
What is mean by monetory policy
Lovely
monetary polices are rules that control the rate of monetary exchange in an economic as a whole.
Ebrima
wealth of the nation
Uhara
important of unemployment
Otwe Reply
Important of unemployed
Otwe
important?
Aneela
While the American heart association suggests that meditation might be used in conjunction with more traditional treatments as a way to manage hypertension
Beverly Reply
in a comparison of the stages of meiosis to the stage of mitosis, which stages are unique to meiosis and which stages have the same event in botg meiosis and mitosis
Leah Reply
how do you find theWhat are the wavelengths and energies per photon of two lines
caroline Reply
The eyes of some reptiles are sensitive to 850 nm light. If the minimum energy to trigger the receptor at this wavelength is 3.15 x 10-14 J, what is the minimum number of 850 nm photons that must hit the receptor in order for it to be triggered?
razzyd Reply
A teaspoon of the carbohydrate sucrose contains 16 calories, what is the mass of one teaspoo of sucrose if the average number of calories for carbohydrate is 4.1 calories/g?
ifunanya Reply
4. On the basis of dipole moments and/or hydrogen bonding, explain in a qualitative way the differences in the boiling points of acetone (56.2 °C) and 1-propanol (97.4 °C), which have similar molar masses
Kyndall Reply
Calculate the bond order for an ion with this configuration: (?2s)2(??2s)2(?2px)2(?2py,?2pz)4(??2py,??2pz)3
Gabe Reply
Which of the following will increase the percent of HF that is converted to the fluoride ion in water? (a) addition of NaOH (b) addition of HCl (c) addition of NaF
Tarun Reply
Practice Key Terms 3

Get the best Algebra and trigonometry course in your pocket!





Source:  OpenStax, Ut austin - principles of chemistry. OpenStax CNX. Mar 31, 2016 Download for free at http://legacy.cnx.org/content/col11830/1.13
Google Play and the Google Play logo are trademarks of Google Inc.

Notification Switch

Would you like to follow the 'Ut austin - principles of chemistry' conversation and receive update notifications?

Ask