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ANACHEM LEC > INTRO TO ANACHEM AND MEASUREMENTS > Flashcards

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
Q

What are the modern (instrumental) equipments?

A

AAS (spectrometer)
UV-Vis Spectrophotometer
NMR (Nuclear Magnetic Resonance Spectroscopy)
HPLC (High-Performance Liquid Chromatography)

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26
Q

True or False: A classical method accounts for about 10% of all
the current analytical work.

A

True

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27
Q

A classical method is ________ sensitive (up to
microgram units)

A

less

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28
Q

Determines one
analyte at a time

A

Classical

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29
Q

Accounts for 90% of the
current analytical work

A

INSTRUMENTAL

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30
Q

Instrumental Method is_________ sensitive

A

Very

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31
Q

May determine
several samples
compounds (multi-analyzer, even>10)

A

Instrumental Method

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32
Q

In Classical Method, it has small concentration
range of ____orders of
magnitude (i.e.
powers of 10)

A

2-3

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33
Q

In Instrumental Method is has more than ___________
of magnitude (i.e.
power of 10)

A

6 orders

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34
Q

It is quicker and
cheaper for large
samples

A

Instrumental

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35
Q

Instrumental Method is more efficient thus, have ________________handling and are more__________.

A

automatic data; reliable

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36
Q

The structured steps in chemical analysis
Involves sample preparation, separation, and
measurement

A

Analytical Process

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37
Q

What are the things involved in Analytical Process

A
  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
Q

Steps of the Analytical Process

A
  1. Problem Definition
  2. METHOD SELECTION
  3. SAMPLING
  4. SAMPLE PREPARATION
  5. ANALYSIS (Separation)
  6. CALCULATION AND REPORTING (Measurement)
39
Q

– 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?

A

PROBLEM DEFINITION

40
Q

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?

A

METHOD SELECTION

41
Q

– 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

A

SAMPLING

42
Q

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)?

A

SAMPLE PREPARATION

43
Q

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

A

ANALYSIS (Separation)

44
Q

– calculate results, interpret/present data and draw
conclusion. Give recommendation.
* Statistical analysis (reliability)
* Report results with limitations/accuracy
information

A

CALCULATION AND REPORTING (Measurement)

45
Q

Samples of about the same size that are
carried through an analysis in exactly the same way

A

REPLICATES

46
Q

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.

A

REPLICATES

47
Q

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.

A

REPLICATES

48
Q

To determine the central value, we can either use the
MEAN or the MEDIAN

A

MEASURES OF CENTRAL VALUE OR TENDENCY

49
Q

the sum of numbers (replicate
measurements) divided by number of measurements
in the set; Similar to average

A

MEAN

50
Q

the middle value in a set of that has been
arranged in numerical (increasing or decreasing)
order

A

MEDIAN

51
Q

Used when a set of data contains an outlier

A

MEDIAN

52
Q

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.

A

outlier

53
Q

The _______ will not discriminate the outlier

A

median

54
Q

Construct the formula of the Mean with these given values:
65.5
66.7
68.8
69.1
69.2
70.0

A

(65. 5 + 66. 7 + 68. 8 + 69. 1 + 69. 2 + 70. 0)/6 = Mean

55
Q

Construct the formula of the Median with these given values:
65.5
66.7
68.8
69.1
69.2
70.0

A

(68. 8 + 69. 1)/2=Median

56
Q

ANALYTICAL MEASUREMENTS(A & P):

A

ACCURACY & PRECISION

57
Q

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.

A

ACCURACY

58
Q

statistically measured
through absolute or relative error

A

Accepted value

59
Q

refers to the agreement between
values in a set of data (closeness of data).

A

PRECISION

60
Q

It describes the reproducibility of
measurements

A

PRECISION

61
Q

PRECISION is Statistically measured through:

A

▪ Standard deviation
▪ Variance
▪ Coefficient of variation
▪ Other measures

62
Q

MEASUREMENT OF ACCURACY: You determine the error first before the accuracy with
these 2 measurements. What are those?

A

ABSOLUTE ERROR, RELATIVE ERROR

63
Q

is equal to the difference
between the actual reading Xi, and the true (or
accepted) value Xt; bears a sign

A

ABSOLUTE ERROR

64
Q

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

A

RELATIVE ERROR

65
Q

EA = Xi – Xt
(lowerscript ang A)

A

(ABSOLUTE ERROR)

66
Q

Et =( (Xi−Xt) / Xt) × 100%

A

(RELATIVE ERROR)

67
Q

Where Xi =

A

actual reading

68
Q

Xt =

A

= true or accepted value

69
Q

the most recognized measure of precision

A

STANDARD DEVIATION

70
Q

May be used to calculate the precision of
measurements for an entire population (σ) or
a sample (s) of the population

A

STANDARD DEVIATION

71
Q

If you have plenty of data, __ is better to use

A

SD

72
Q

If we’re dealing with only 2 replicates,
you can opt for measurement for
_______.

A

Range

73
Q

RSD = (S / x̄)
where:
s – (?)
x̄ – (?)

A

sample standard deviation, mean

74
Q

Is basically the RSD in percentage

CV = (S/x̄) × 100%

A

COEFFICIENT OF VARIATION

75
Q

The square of the Standard Deviation

A

VARIANCE

76
Q

The sample variance (s^2) is

A

an estimate
of the population variance (σ2)

77
Q

The difference between the largest value
in the set and the smallest

A

SPREAD OR RANGE

78
Q

ω = XH – XL
where: XH =?
XL = ?

A

Highest Value; Lowest Value

79
Q

consists of all certain digits in a
measurement plus the first uncertain digit

A

SIGNIFICANT FIGURES

80
Q

Laboratory investigations usually involve the
taking of and ____________________ of measurements.

A

interpretation

81
Q

RULES FOR SIGNIFICANT FIGURES:

A

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
Q

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.

A

lowest

83
Q

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 ______________.

A

significant figures

84
Q

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.

A

logarithm

85
Q

In an ___________________________of a number, keep as many digits
as there are digits to the right of the decimal point
in the original number.

A

antilogarithm

86
Q

Antilog is basically a reverse function of Log.
You can calculate it by pressing _____ key
before pressing the log key.

A

[Shift]

87
Q

RULES FOR ROUNDING OFF NUMBERS:
If the digit to be dropped is greater than 5, the last
retained digit is increased by ___.

A

one

88
Q

If the digit to be dropped is less than 5, the last
remaining digit is left _______.

A

as it is

89
Q

If the digit to be dropped is 5, and if any digit following
it is not zero, the last remaining digit is increased by
____.

A

one.

90
Q

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 ____.

A

odd; even

ANACHEM LEC (7 decks)

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