Not All Acids and Bases Are Created Equal

Strong acids completely dissociate in water weak acids don t. Strong acids = high Ka = low pA a. 

There are acids and then there are ACIDS. Acids such as HCI and H2SO4 are strong acids. When you add a mole of HCI to water, you get a mole of protons (HsO ) and a mole of Cl. HCI and other strong acids are, in fact, stronger acids than HsO so that the equilibrium 

The strength of an acid can be defined by the tendency of the acid to give up its proton to water. The stronger the acid, the larger the equilibrium constant for the reaction 

For strong acids, this equilibrium constant is greater than 1, and for weak acids, Ka is much less than 1. For most acids you find in biochemistry, Ka is much less than 1 and proton transfer from HA to water is not very favorable (nor complete). 

The pS a is one of those unfortunate concepts that turns everything around. It also puts acid strengths on a logarithmic scale similar to earthquakes and other natural disasters. Logarithms will be discussed later. For right now, just remember that stronger acids have lower pS a s. 

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