[Kartiky14]

How do we determine the strength of bases?? (not alkalis)

[dazza95]

Think in terms of ph,
pH stands for potential of hydrogen and is the measure of acidity running from 0 to 14 (the most basic or most alkaline). The lower the pH level, the more acidic the solution is as acids will have a high concentration of hydrogen ions. Pure water has a pH of 7.0 (neutral)

A solution can be described as acidic, neutral, or basic depending upon the pH level of that solution. On a chemical level under the Lowry Brønsted system an acid is defined as a proton (H+) donor, while a base (or alkali) is a proton (H+) acceptor. pH can be calculated using the formula; pH=-log10[H^+] where [H+] is the concentration of H+ ions per unit of volume. The reaction of an acid is given in the form; HA ⇌H^++A^- where HA is the acid and A- is the base. This can be placed into the equilibrium constant formula to determine the concentration of H+ ions in molar form for the pH formula.
Ka=([products])/([reactants])
Ka=([H^+ ][A^-])/([HA])
From this equation, if Ka is high then the acid is weak, if Ka is low then the acid is strong. Using this formula, the molarity of the H+ ions can be determines and then used in the pH formula. Because this equation is logarithmic it is expected that 0.1 molar of H+ ions will have a pH of 1 and if it was 0.0001 molar, it would have a pH of around 4. pKa is used more often in practice rather than Ka as it is a logarithmic measure just like pH. Every pH change of 1 means that there is 10,000 times more H+ ions per unit volume. pKa is the –log(10) of the equilibrium of the acid dissociation constant.
pKa=-log10Ka
If pKa is high then the acid is weak.

[PIQgoogleme]

^^^
the pH scale doesn't run from 0 to 14. What if you had, say 2.0 M H₂SO₄ (aq)?

Find it's K_b If that doesn't mean anything to you, read up on the pH system and equilibrium constants, and come back to us with anything you're still unclear on.

[Borek]

Every pH change of 1 means that there is 10,000 times more H+ ions per unit volume.

Huh?