1. CHEM 106/320: Fundamentals of Analytical Chemistry
Erika Portero
CHEM 400

2. Goals and Objectives of CHEM 160/320
Data Analysis and Statistics
Solution Equilibria
Emphasis on acid/base equilibria
Electrochemistry
Spectroscopy
Emphasis on spectrophotometry and fluorescence

3. Data Analysis and Statistics
Accuracy: Relationship between a measured value and the actual value.
Precision: Reproducibility of the measurement .
Average or Mean: The sum of all the measured values divided by the number of measurements.
Range: The difference between the lowest and highest values (in the data set).
Mode: Most frequently occurring number found in a data set.
Standard Deviation: measurement used to quantify the amount of variation or dispersion of a set of data values

4. Data Analysis and Statistics
Gaussian Distribution
It is a two parameter function: µ, the mean and σ, the standard deviation.

5. Data Analysis and Statistics
Confidence interval
Ex. 95% confidence interval – “ we are 95% confident that the true mean lies within the confidence interval”
T test – tests the difference of two averages
P sig – Probability that the difference in the data set is real. If P sig > 0.95 then significantly different
P insig – Probability that the difference in two sets is due to random error
t = x ± ts , |x 1 – x 2|
t calc = √n
√s 12/ n 1+ s 2 2 /n 2

6. Data Analysis and Statistics
F test = tests the difference of two standard deviations
F calc =
If F calc > F table, then the standard deviations are significantly different
If F calc < F table, then calculate S pooled and t calc
If t calc is > t tab, then the means are significantly different
S21
S22

7. Solutions and Dilutions
Making Solutions (Rules ):
Graduated cylinders are considerably less accurate and precise than glass transferring pipettes
Larger glassware has relative less uncertainty
Multiple dilutions introduce more error
Glassware is designed to hold a specific volume only at a stated temperature
Dilutions
C1V1=C2V2

8. The importance of Ionic Strength
Solubility – the amount of solid that dissolves in a solution , expressed in units if mol/L .
Ksp – Solubility product constant
aA(s)⇌cC(aq)+dD(aq)
Ksp=[C]c[D] d
Ionic Strength – Measure of the total ion concentration of a solution. It is given the symbol µ and has units of molarity.
Activity coefficient, β ,that changes with ionic strength
Ksp=βc[C]cβd[D] d

9. The importance of Ionic Strength

10. Multiple Equilibria AgCN(s) Ag+ + CN-
Ksp = 2.19 X 10 E-16 = [Ag+ ][CN-]
As the pH of the solution decreases, then HCN is more abundant.
CN- is a base. In a more acidic environment, reacts with H + to form HCN
This is an example of competing reactions and the effect pH has on these reactions

11. Acid/Base Equilibria
When pH = pKa , the same amount of both ions co- exist at the same time
Example : H2CO3, Carbonic acid

12. Electrochemistry
Galvanic Cell – uses spontaneous chemical reactions to generate electricity
Oxidation : Loss of electron and Reduction : Gain of electron
Chemistry and Electricity:
Electric charge q=n F , F= x10E4 C/mol
Free energy and electric potential ∆G = -nFE