The Henderson-Hasselbach equation:  pH = pKa + log [A-]/[HA], which is just a variation of the equilibrium equation of Ka = [H+][A-]/[HA]   The Ka = 2 x 10-5 M.  So we compute pKa = -log Ka:  pKa = -log 2 x 10-5 = -(-4.70) = 4.70  (I think it's acetic...

Let's use the Henderson-Hasselbach equation to define two conditions.  Condition 1 is before the strong acid is added, and Condition 2 is after it is added.   Condition 1:  pH = pKa + log [A-]/[HA] Note that because [A-] = [HA], the pH = pKa:   pH = pKa +...

Questions like these test your ability to sum up the energy inputs to a substance that also undergoes phase changes.  With this question, you have H2O which transitions from a solid phase (ice) to the liquid phase (water) to the gas phase (steam).   H2O (s) => H2O (l) =>...

I think you are missing a question here.  If I were to guess, the question is "What's the total volume of the bucket?"  Right?  I will assume that is the question.   As with all word problems, there are two parts.  The first part is to express the words,...

This instructs you in turning word problems into mathematical (algebraic) expressions that you can solve.   Let's define the variable P as the number of pens that Pat has (it's often easy to use the names to get the variables).   Similarly, S is the variable for the number...

This URL is a good presentation of the problem that you pose:  http://www.oswego.edu/~srp/stats/6895997.htm   In the figure on this page, you can see the normal distribution.  The top of the curve represents the mean value of the data.  For the standard normal distribution,...

I am going to restate what I believe you are trying to say, because it's not quite clear to me.   There are two investment amounts, P1 and P2.   P1 is invested at an 8% yield.   P2 is invested at \$2100 less than the amount P1 at a 5% yield.   Therefore,...