Hydrolysis and Buffers, take 2
Hydrolysis sectionIn this part of the experiment you will test several different salt solutions (in a spot plate) with pH paper determine their acidity or basicity and then determine which solution is which.
Re-read section in your text about hydrolysis and your lecture notes on hydrolysis to prepare you for the experiment.Buffers
A mixture of relatively large amounts of weak acid and its salt or a weak base and its salt is known as a buffer. Buffers have the property of maintaining a relatively constant pH even when considerable acid or base has been added.Re-read section of your text on buffers to prepare for this experiment.
For each step number in the buffer section, give nice organized tables of data (volumes, pH measurements, whatever) and words to tie them together (it should be clear what you are doing) and answer all the questions posed.Oh and that pesky commentary section, don't forget that. Remember, getting better results or the lab getting done faster are not valid 'how to make this a better learning experience' answers.
Prelab Questions: (worth 5 points)
1. Calculate the pH of a 0.87 M NaCN solution. Solve it exactly (no 'assume x=0.1')
HINT: NaCN dissociates into Na+ (an unexciting acid) and CN-, the conjugate base of HCN. You can look up the Ka for HCN, and therefore calculate the Kb for the BASE, CN-. It is this equation (Kb) that is your equilibrium expression for this problem.
2. What is initial concentration of a sodium acetate if the pH (at equilibrium) is measured to be 9.30? HINT: Same sort of thing as question 1, sodium acetate dissociates into Na+ and acetate ion (a base)......
~MEO 22 Mar 06