I've made a "trainer" so to speak for some plain weak acid/ weak base problems. Please TRAIN yourself on these and get good at it. - Dr. McCord
Each of the links below will open a new page with an Acid/Base Question. You WILL need to look up the values for Ka and Kb from our listing on the gchem site.
Rules for Engagement: The server will randomly PICK one of the many acids or bases (or salts there of) from our list on gchem. The server also randomly picks concentrations for you to use in your calculations.
Each set of picks has a specific 5-digit code that can be directly used if you ever want that problem again or want to do the same problem as a friend. Just enter the same 5-digit code and you'll get the same question. Click on random and the computer picks a new code and a new question set.
The SOLUTIONS: Every problem has the solution right below it and you can reveal the parts separately. Right now the only algebraic solution is the full quadratic formula solution because it is the most accurate under ALL conditions. The algebra short-cut known as "the assumption" is shown after the full quadratic answer. A percentage is shown on how good the assumption is in that case. A comment about the assumption is also made.
Below are the two links to the pages that calculate all the points for a titration curve for "all" cases. Pick the page that you prefer - acid titrated with base, or base titrated with acid.
Although, the following method is not the most efficient way to solve problems on an exam, it is a really good way to THINK and CONCEPTUALIZE acid/base problems.
Imagine that you start with a weak acid, HA, and then allow it to continually ionize step by step... one proton, then another, and another. Now think about "snapshots" of this on every step. You would actually HAVE the concentrations of all THREE of the parts of the mass action expression for Q and K. So you can calculate Q and/or K on every step and the percent ionization - just calculate it. You can do this easily in a spreadsheet program like Excel... or use this widget I made.
Just enter your starting conc for HA and the increment (decrement) you want to use to the successive ionizations.
Here is a whole helpsheet on how to build and plot your own Fraction of Species diagrams for polyprotics.