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INTRO TO ANACHEM AND MEASUREMENTS Flashcards

1
Q

Is a branch of chemistry involved with the analysis of
chemical substances
; Characterization of matter
ANALYSIS

A

ANALYTICAL CHEMISTRY

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2
Q

In Analysis
‘Ana’ meaning ___ and
‘lyein’ meaning _______

A

up; loosen

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3
Q

Defined as the identification and determination of
the relative amounts of one or more components in a
mixture

A

ANALYSIS

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4
Q

two major areas of analytical chemistry

A

Qualitative Analysis and Quantitative Analysis

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5
Q

identification of
substances of interest
* Answers the question, “What is in the
sample?

A

QUALITATIVE ANALYSIS

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6
Q

determination of
concentration or amount of substances present in a
given sample
* Answers the question, “How much is in the
sample?”

A

QUANTITATIVE ANALYSIS

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7
Q

ANALYTICAL METHODS:

A

CLASSICAL (CHEMICAL OR WET); MODERN (INSTRUMENTAL)

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8
Q

Methods in which basic types of equipment are used
based on simple chemical analysis

A

CLASSICAL (CHEMICAL OR WET)

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9
Q

2 METHODS OF CLASSICAL METHOD

A

Gravimetric Method and Volumetric Method

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10
Q

determine the mass of
the analyte or some compound chemically related
to it

A

Gravimetric Method

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11
Q

measure the volume of a
a solution containing sufficient reagent to react
completely with the analyte

A

Volumetric Method

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12
Q

3 Methods of Modern Analytical Method

A

Electroanalytical Method, Spectroscopic Method, Miscellaneous Method

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13
Q

measurement of
electrical properties (voltage, current, resistance,
quantity of electrical charge)

A

Electroanalytical Method

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14
Q

based on the
measurement of the interaction between
electromagnetic radiation and analyte atoms or
molecules, or the production of such radiation by
analytes

A

Spectroscopic Methods

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15
Q

measurement of such
quantities as:
▪ mass-to-charge ratio
▪ rate of radioactive decay
▪ heat of reaction
▪ rate of reaction
▪ sample thermal conductivity
▪ optical activity
▪ refractive index

A

Miscellaneous Methods

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16
Q

In two types of Analytical Method (Classical and Modern) which is more efficient?

A

Modern (Instrumental)

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17
Q

State if this method is classical/instrumental and the example it has:
Titrimetric

A

Classical
Example: Acid/Base, Redox, Precipitation Titrations

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18
Q

State if this method is classical/instrumental and the example it has:
Gravimetric

A

Classical
Example: Analysis of inorganic ions (constant mass)

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19
Q

State if this method is classical/instrumental and the example it has:
Separation

A

Classical; Example: TLC, PC, CC, IEC
Instrumental; Example: GLC, HPLC

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20
Q

State if this method is classical/instrumental and the example it has:
Electrochemical

A

Classical; Example: Potentiometric, conductimetric titrations
Instrumental; Example: Polarography, ion selective electrodes

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21
Q

State if this method is classical/instrumental and the example it has:
Spectroscopy Absorption and Spectroscopy Emission

A

Instrumental
Example: UV, IR, NMR, ESR, AAS, Flame Photometry, AES, MS

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22
Q

State if this method is classical/instrumental and the example it has:
Nuclear/X-ray

A

Instrumental
Example: MS (isotopes), X-ray fluorescence, NA

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23
Q

State if this method is classical/instrumental and the example it has:
Thermal

A

Instrumental
Example: DTA, TGA, DSC

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24
Q

State if this method is classical/instrumental and the example it has:
Combination Techniques

A

Instrumental
Example: GS/MS, GC/IR, HPLC, MS

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25
What are the modern (instrumental) equipments?
AAS (spectrometer) UV-Vis Spectrophotometer NMR (Nuclear Magnetic Resonance Spectroscopy) HPLC (High-Performance Liquid Chromatography)
26
True or False: A classical method accounts for about 10% of all the current analytical work.
True
27
A classical method is ________ sensitive (up to microgram units)
less
28
Determines one analyte at a time
Classical
29
Accounts for 90% of the current analytical work
INSTRUMENTAL
30
Instrumental Method is_________ sensitive
Very
31
May determine several samples compounds (multi-analyzer, even>10)
Instrumental Method
32
In Classical Method, it has small concentration range of ____orders of magnitude (i.e. powers of 10)
2-3
33
In Instrumental Method is has more than ___________ of magnitude (i.e. power of 10)
6 orders
34
It is quicker and cheaper for large samples
Instrumental
35
Instrumental Method is more efficient thus, have ________________handling and are more__________.
automatic data; reliable
36
The structured steps in chemical analysis Involves sample preparation, separation, and measurement
Analytical Process
37
What are the things involved in Analytical Process
1. Sample Preparation 2. Measurement 3. Signal belonging, - guarantee, - selection, -parameter 4. Calibration 5. Chemometrics 6. Data evaluation and interpretation 7. Chemometric Data Analysis
38
Steps of the Analytical Process
1. Problem Definition 2. METHOD SELECTION 3. SAMPLING 4. SAMPLE PREPARATION 5. ANALYSIS (Separation) 6. CALCULATION AND REPORTING (Measurement)
39
– identify the problem and formulate questions * What is the problem? What needs to be found? Qualitative and/or quantitative? * What will the information be used for? Who will use it? * When will it be needed? * How accurate and precise does it have to be? * What is the budget?
PROBLEM DEFINITION
40
select method of analysis  FACTORS * Sample type, size of sample, sample preparation * Concentration and range (sensitivity needed) * Selectivity needed (interferences) * Accuracy/precision needed * Tools/instruments available * Expertise/experience * Cost * Speed * Does it need to be automated? * Are methods available in chemical literature? * Are standard methods available?
METHOD SELECTION
41
– obtain bulk sample and extract smaller laboratory sample from bulk  Process of collecting a small mass of a material whose composition accurately represents the bulk of the material being sampled FACTORS * Sample type/homogeneity/size * Size: macro, semi-macro, micro, ultra * Type: major, minor, trace, ultra * Sampling statistics/errors
SAMPLING
42
prepare sample for analysis  FACTORS * Solid, liquid, or gas? * Dissolve? * Ash of digest? * Chemical separation or masking of interferences needed? * Need to concentrate analyte? * Need to change (derivatize) the analyte for detection? * Need to adjust solution conditions (pH, add reagents)?
SAMPLE PREPARATION
43
analytical measurement of the analyte in question  Perform any necessary chemical separations: * Distillation * Precipitation * Solvent extraction * Solid phase extraction * Chromatography (may be done as part of the measurement step) * Electrophoresis (may be done as part of the measurement step)  Perform the Measurement: * Calibration * Validation/controls/blanks * Replicates
ANALYSIS (Separation)
44
– calculate results, interpret/present data and draw conclusion. Give recommendation. * Statistical analysis (reliability) * Report results with limitations/accuracy information
CALCULATION AND REPORTING (Measurement)
45
Samples of about the same size that are carried through an analysis in exactly the same way
REPLICATES
46
To improve the reliability and to obtain information about the variability of results, two to five portions, AKA replicates of a sample are carried through an entire analytical procedure.
REPLICATES
47
Individual results from a set of measurements are seldom the same, so we usually consider the “best” estimate to be the central value for the set.
REPLICATES
48
To determine the central value, we can either use the MEAN or the MEDIAN
MEASURES OF CENTRAL VALUE OR TENDENCY
49
the sum of numbers (replicate measurements) divided by number of measurements in the set; Similar to average
MEAN
50
the middle value in a set of that has been arranged in numerical (increasing or decreasing) order
MEDIAN
51
Used when a set of data contains an outlier
MEDIAN
52
a result that differs significantly / far away from others in the set. It can have a significant effect on the MEAN of the set but has NO effect on the MEDIAN.
outlier
53
The _______ will not discriminate the outlier
median
54
Construct the formula of the Mean with these given values: 65.5 66.7 68.8 69.1 69.2 70.0
(65. 5 + 66. 7 + 68. 8 + 69. 1 + 69. 2 + 70. 0)/6 = Mean
55
Construct the formula of the Median with these given values: 65.5 66.7 68.8 69.1 69.2 70.0
(68. 8 + 69. 1)/2=Median
56
ANALYTICAL MEASUREMENTS(A & P):
ACCURACY & PRECISION
57
describes the nearness of an experimental value or a mean to the true value. Although the true value can never be exactly known, accepted value is often used.
ACCURACY
58
statistically measured through absolute or relative error
Accepted value
59
refers to the agreement between values in a set of data (closeness of data).
PRECISION
60
It describes the reproducibility of measurements
PRECISION
61
PRECISION is Statistically measured through:
▪ Standard deviation ▪ Variance ▪ Coefficient of variation ▪ Other measures
62
MEASUREMENT OF ACCURACY: You determine the error first before the accuracy with these 2 measurements. What are those?
ABSOLUTE ERROR, RELATIVE ERROR
63
is equal to the difference between the actual reading Xi, and the true (or accepted) value Xt; bears a sign
ABSOLUTE ERROR
64
describes the error in relation to the magnitude of the true value, and may, therefore, be more useful than considering the absolute error in isolation
RELATIVE ERROR
65
EA = Xi – Xt (lowerscript ang A)
(ABSOLUTE ERROR)
66
Et =( (Xi−Xt) / Xt) × 100%
(RELATIVE ERROR)
67
Where Xi =
actual reading
68
Xt =
= true or accepted value
69
the most recognized measure of precision
STANDARD DEVIATION
70
May be used to calculate the precision of measurements for an entire population (σ) or a sample (s) of the population
STANDARD DEVIATION
71
If you have plenty of data, __ is better to use
SD
72
If we’re dealing with only 2 replicates, you can opt for measurement for _______.
Range
73
RSD = (S / x̄) where: s – (?) x̄ – (?)
sample standard deviation, mean
74
Is basically the RSD in percentage CV = (S/x̄) × 100%
COEFFICIENT OF VARIATION
75
The square of the Standard Deviation
VARIANCE
76
The sample variance (s^2) is
an estimate of the population variance (σ2)
77
The difference between the largest value in the set and the smallest
SPREAD OR RANGE
78
ω = XH – XL where: XH =? XL = ?
Highest Value; Lowest Value
79
consists of all certain digits in a measurement plus the first uncertain digit
SIGNIFICANT FIGURES
80
Laboratory investigations usually involve the taking of and ____________________ of measurements.
interpretation
81
RULES FOR SIGNIFICANT FIGURES:
RULE 1: All nonzero digits in a measurement are significant. RULE 2: Interior zeros (zeros between nonzero numbers) are significant. RULE 3: Leading zeros (zeros at the beginning of a number) are NOT significant. RULE 3: Trailing zeros (zeros at the end of a number)
82
When adding or subtracting measurements with significant figures, the result has the same number of decimal places as the measurement with the ________________ number of decimal places.
lowest
83
When multiplying or dividing measurements with significant figures, the result has the same number of significant figures as the measurement with the lowest number of ______________.
significant figures
84
In a ________________ of a number, keep as many digits to the right of the decimal point as there are significant figures in the original number.
logarithm
85
In an ___________________________of a number, keep as many digits as there are digits to the right of the decimal point in the original number.
antilogarithm
86
Antilog is basically a reverse function of Log. You can calculate it by pressing _____ key before pressing the log key.
[Shift]
87
RULES FOR ROUNDING OFF NUMBERS: If the digit to be dropped is greater than 5, the last retained digit is increased by ___.
one
88
If the digit to be dropped is less than 5, the last remaining digit is left _______.
as it is
89
If the digit to be dropped is 5, and if any digit following it is not zero, the last remaining digit is increased by ____.
one.
90
If the digit to be dropped is 5 and is followed only by zeroes, the last remaining digit is increased by one if it is ___, but left as it is if ____.
odd; even

ANACHEM LEC (7 decks)

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