pH is a measure of how acidic or alkaline a solution is - in other words, whether there are more free hydrogen (H+) or hyrdoxyl (OH-) ions in it. A neutral solution (pH 7) is one where H+ and OH- are balanced: acids (pH <7) have more H+, while bases (pH >7) have more OH- . Blood has a pH of 7.4, which makes it slightly basic.
Work Step by Step
p. 40 shows a chart with the pH of common solutions