Experiment 20Page 215Dr. Scott Buzby Ph.D.

An acid-base titration is the determination of the concentration of an acid or base by exactly neutralizing the acid/base with an acid or base of known concentration

This allows for quantitative analysis of the concentration of an unknown acid or base solution

It makes use of the neutralization reaction that occurs between acids and bases and the knowledge of how acids and bases will react if their formulas are known )(2)()(3 2 laqaq OHOHOH

The burette should be rinsed with the standard solution and an Erlenmeyer flask with distilled water

Add a known volume of the unknown to the Erlenmeyer flask, along with a small amount of the indicator chosen

The known solution should then be allowed out of the burette, into the conical flask. At this stage we want a rough estimate of the amount of this solution it took to neutralize the unknown solution

Three more titrations should be performed, this time more accurately, taking into account roughly where the end point will occur. The readings on the burette at the end point should be recorded, and averaged to give a final result. The end point is reached when the indicator just changes color permanently

Molarity

Molarity of Unknown

% KHP in Sample

BBAA MVMV

SolutionL

massmolarsampleofgramsM

/

SampleofMass

KHPgKHP %

The standard deviation of a statistical population, a data set is the square root of its variance

Standard deviation is a widely used measure of variability or dispersion, it shows how much variation there is from the "average" (mean)

A low standard deviation indicates that the data points tend to be very close to the mean, whereas high standard deviation indicates that the data are spread out over a large range of values

1

2

m

XSD i

Consider a population consisting of the following values:

There are eight data points in total, with a mean (or average) value of 5:

To calculate the population standard deviation, first compute the difference of each data point from the mean, and square the result:

Next divide the sum of these values by the number of values and take the square root to give the standard deviation:

Therefore, the above has a population standard deviation of 2

Report Sheet – Page 223

Questions – Page 224

Pre-Lab Experiment 24 – Page 267