Chap 6 & 7 Flashcards
SP. 6.1b. I.Describe how TITRATION used to obtain [ion] is relevant to TDS measurement. Some titration examples
A known volume V1 is titrated by a standard of Known volume V2 and [M2] to the endpoint (visual) which indicates the reaction is at the equilibrium and the [M1] is determined by stoichiometry. if the stoichiometry is 1:1, therefore, M1=(M2V2)/V1
Some eg. of this titration:
- AB: [UNK acid], P, M points are used to determine [Alk] and [HCO3-] & [CO3]
- Redox: the titration of residual Chloride awa COD involve in redox titration.
- pptn: the titration for Chloride and AgNO3
- complex formation: titration of Hardness, Calcium and Magnesium
SP.6.1b II. Describe how ION Chromatography (IC)
the use of an ion exchange column to analyze for anions and involving a conductivity detector.
Most [anion] can be defined thru calibration curve except CO3, HCO3 because of suppressor
SP6.1b III. Atomic Absorption Analysis (AA)
Light is directed thru the sample and the attenuation(sự làm yếu) of the intensity is used to determine the concentration of the Unknown when calibration curve is determined
Eg. sodium, calcium, copper & zinc
SP6.1b IV.Atomic Emission Analysis (ICP)
The wavelength and the intensity of the emitted light is used to determine the identity and [UNK} while calibration curve obtained
Eg. Most metals
SP6.1 V.Potentiometric Analysis (Ion-selective Electrode or ISE)
An electrode is designed that measure the activity of a particular ion via a reaction at either an anode or at a cathode. The calibration curve obtained to determine the [UNK]
Eg. Cl, F, ammonium, hydronium ( OH), NH4, metals such as silver
SP.6.2.c 3 methods used to obtain TDS
Evaporation/ weighing
Conductivity
Ion Analysis
TDS - Evaporation/ Weighing method
Known Vsample placed in a preweighed container and then dried at 105C. TDS in mg/L at a constant weight= The difference in weight/ Vsample.
Advs: cheap, not required lots of work, time-consuming
Disadvs: significant error from some substances are volatile and some change form when heated and some organics are not volatile leading to confusion between TDS and Dissolved Organics
TDS - Conductivity
Compare the measured conductivity value of the sample to the standard NaCl(ap). The TDS is reported as though the sample was also made up of NaCl
Advs: cheap, easy to use, quick, does not require a lot of skill
Dis: values are only approximate
TDS - Ion Analysis
individual ion are analyzed using a variety of technique ranging from the very expensive ICP MS to relatively inexpensive ISE, total TDS = all [ion] in mg/L
Dis: time consuming, expensive
Advs: very accute
SP.6.3b. Describe how molecules absorb waves in the
Microwave: molecules rotate
IR: molecules vibrate
VIS or V: electronic excitation occur
gamma ray: inner shell electrons are excited
6.3d Define T and %T
T: the amount of light transmitted thru a solution.
%T: the percentage of light transmitted by the substance relative to the reference blank
Value of Absorbance
A= 2 - log %T
6.4d. Analyte
the components of a sample being determined
6.4d. Blank solution
containing reagents and solvents, but NO analyte
6.4d. Standard solution
a solution in which the concentration of a solute is known with high reliability
6.4d. Why Fe colorimetric Analysis needs both blank and set of standards
- blank: used to calibrate the spectrometer to zero that means t
standard: used to predict the relationship btw absorbance and [ ]
6.4e. 4 Advantages of ICP instruments
- can determine many elements in an analysis
- large liner range & low detection limits
- very few interferences (ionization, chemical & interelement interferences are eliminated
- can detect elements that thermally decomposite at the lower temps of the flames used in AA.
6.4e. linear range
concentration range where the measured absorbance follows Beer’s law ( linear relationship btw absorbance and [ ] : A=Ebc