Calling this equation an awkward inverse may be too polite. It is a major source of confusion and provides no extra information. However, you can read more about it if you wish. The pH is the negative logarithm of the hydrogen ion concentration. A complete definition requires that the logarithm is defined as being to the base ten and the concentration be measured as activity in moles per liter.
Confusion arises because, as the acidity increases, the pH decreases.
To learn more about pH, play in the pH playground . 3 Logarithm is another source of confusion in acid base balance and is responsible for the mistaken impression that the body maintains remarkably tight control over its hydrogen ion concentration - it doesn't. 40 mmHg PCO 2 is the partial pressure of carbon dioxide. The end-exhaled value is usually very similar. Under anesthesia, the end exhaled value is often lower than arterial value, due to several contributing factors.