Lecture 1: Introduction to Analytical Chemistry Flashcards by elyssa katrina

TWO TYPES OF DIGITS

EXACT AND INEXACT

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NUMBERS NOT MEASURED USING INSTRUMENTS
INCLUDES DEFINED NUMBERS
INFINITE NUMBER OF SFS
DOESN’T AFFECT ACCURACY/PRECISION OF CALCULATIONS OR PRECISION

EXACT NUMBERS

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WHAT TYPE OF DIGITS ARE THESE?

1 FOOT = 12 INCHES
100 YRS IN A CENTURY

EXACT NUMBERS

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NUMBERS WHICH ARE MEASUREMENTS MADE WITH INSTRUMENTS

- WITH INHERENT UNCERTAINTY FROM THE INSTRUMENTS

INEXACT NUMBERS

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INDICATES THE PROBABLE UNCERTAINTY IN AN EXPERIMENTAL MEASUREMENT

SIGNIFICANT FIGURES

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ALL THE DIGITS THAT ARE “CERTAIN” + FIRST UNKNOWN DIGIT

SIGNIFICANT FIGURES

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TRUE OR FALSE:

NON ZERO DIGITS ARE ALWAYS SIGNIFICANT

TRUE

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TRUE OR FALSE: ZERO IS SIGNIFICANT WHEN IT IS BETWEEN 2 NON-ZERO DIGITS

TRUE

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TRUE OR FALSE:

THE FINAL/TRAILING ZEROS OF A NUMBER IS SIGNIFICANT

FALSE

- ONLY FOR THE DECIMAL PORTION

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TRUE OR FALSE:

ZEROS BETWEEN DECIMAL POINT AND NON-ZERO DIGITS ARE SIGNIFICANT

FALSE

- THEY SERVE AS PLACEHOLDERS ONLY

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ADDITION/SUBTRACTION

- ROUND ANSWER TO ______ NO. OF ______ OF ANY OF THE GIVEN NUMBERS

LEAST, DECIMAL PLACES

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MULTIPLICATION/DIVISION

- ROUND ANSWER TO _______ NO. OF _______ OF ANY OF THE GIVEN NUMBERS

LEAST, SFS

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SF IN LOGARITHM

NO. OF SFS IN THE ORIGINAL NUMBER = NO. OF SFS TO THE RIGHT OF DECIMAL POINT

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SF IN ANTILOGARITHM

NO. OF SFS OF ANSWER = NO. OF SIGNIFICANT DECIMAL PLACES IN GIVEN

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SHOULD ROUNDING OFF BE DONE DURING CALCULATIONS?

NO. AT THE END ONLY.

- ROUND OFF ONLY FINAL RESULT. PRELIMINARY ROUNDING OFF OF RESULTS IS DISCOURAGED

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WHY SOULD ROUNDING OFF BE MINIMIZED DURING CALCULATIONS?

TO MINIMIZE DEVIATION OF FINAL ANSWER FROM CORRECT VALUE

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INDICATE NO. OF SFS
A. 0.0050
B. 3000
C. 1.5 x 10^-2
D. 500.0
E. 1.5050 x 10^3

A. 2
B. 1
C. 2
D. 4
E. 5

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ROUND OFF ACCORDING TO SPECIFIED NO. OF SFS
A. 15.9994 (4)
B. 15.515 (4)
C. 254.5 (3)
D. 14.5001 (2)

A. 16.00
B. 15.52
C. 255
D. 15

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PERFORM OPERATION. OBSERVE CORRECT NO. OF SFS

15.12 mL x 19.25 mL x 2.07 mL

602.4942 –> 602 (3 SF)

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PERFORM OPERATION. OBSERVE CORRECT NO. OF SFS

4.5 in - 1.258 in

3,242 –> 3.2 (1 DECIMAL PLACE ONLY)

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(2.34 - 1.2) x 0.105

1.1 x 0.105 = 0.1155 –> 0.12 (2 SF)

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WHAT ARE THE WAYS OF EXPRESSING SOLUTION CONCENTRATION?

MMPPN

MOLARITY
MOLALITY
PERCENT COMPOSITION
PARTS PER MILLION
NORMALITY

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MOLES OF SOLUTE DIVIDED BY LITERS OF SOLUTION

MOLARITY (M)

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FORMULA AND UNITS OF MOLARITY

FORMULA: M = moles solute/L solution

UNITS: mol/L or M

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MOLES OF SOLUTE DIVIDED BY KILOGRAMS OF SOLVENT

MOLALITY (m)

FORMULA AND UNITS OF MOLALITY

FORMULA: m = moles solute/kg solvent UNIT: mol/kg or m

THREE TYPES OF PERCENT COMPOSITION

A. %w/w - % weight per weight B. %v/v - % volume per volume C. %w/v - %weight per volume

FORMULA FOR %w/w

%w/w = (g solute/g solution) x 100%

FORMULA FOR %v/v

%v/v = (mL solute/mL solution) x 100%

FORMULA FOR %w/v

%w/v = (g solute/mL solution) x 100%

FORMULA FOR ppm

EITHER %w/w or %w/v ppm = (g solute/g solution) x 10^6 ppm = (g solute/mL solution) x 10^6

FORMULA FOR ppb

EITHER %w/w or %w/v ppm = (g solute/g solution) x 10^9 ppm = (g solute/mL solution) x 10^

NUMBER OF EQUIVALENTS OF SOLUTE IN 1L SOLUTION

NORMALITY (N)

FORMULA FOR NORMALITY

N = no. eq solute/L solution

DESCRIBE THE AMOUNT OF A CHEMICAL SPECIES JUST LIKE MOLES

EQUIVALENTS (eq) OR MILLIEQUIVALENTS (meq)

MOLARITY: NORMALITY = MOLES: _______

EQUIVALENTS

MOLARITY: ______ = MOLES: EQUIVALENTS

NORMALITY

THIS IS THE DEFINITION OF THE "EQUIVALENT" AT THE EQUIVALENCE POINT OF ANY TITRATION

NO. OF eq ANALYTE PRESENT = NO. OF eq REAGENT ADDED OR NO. OF meq ANALYTE PRESENT = NO. OF meq REAGENT ADDED

WHY IS THERE NO NEED TO DERIVE THE STOICHIOMETRY BETWEEN THE ANALYTE AND TITRANT?

BECAUSE WE JUST HAVE TO CORRECTLY DEFINE THE eq OR meq FOR EACH TYPE OF REACTING SPECIES

THE AMOUNT OF SUBSTANCE CONTAINED IN ONE EQUIVALENT CAN VARY DEPENDING ON THE _________

TYPE OF REACTION

FORMULA FOR CALCULATING THE NUMBER OF EQUIVALENTS PRESENT IN A SAMPLE

no. eq = mass in g/EW EW = EQUIVALENT WEIGHT OF ANALYTE

WHAT IS EW?

EQUIVALENT WEIGHT OF THE ANALYTE

FORMULA FOR CALCULATING THE EW

EW = FW/n ``` FW = FORMULA WEIGHT OF ANALYTE n = FACTOR THAT DEPENDS ON TYPE OF CHEMICAL REACTION ```

THIS IS THE FACTOR THAT DEPENDS ON THE TYPE OF CHEMICAL REACTION BETWEEN ANALYTE AND TITRANT

factor n

THIS CAN BE USED TO CONVERT MOLARITY TO NORMALITY AND VICE VERSA

factor n

HOW IS THE RELATIONSHIP OF M AND N EXPRESSED IN AN EQUATION

N = n x M

TYPES OF CHEMICAL REACTION BETWEEN THE ANALYTE AND THE TITRANT

CARP COMPLEXATION ACID-BASE (NEUTRALIZATION) REDOX PRECIPITATION

FOR A NEUTRALIZATION REACTION, WHAT IS n?

NUMBER OF H+ IONS THAT AN ACID DONATES OR THAT A BASE ACCEPTS

FOR A PRECIPITATION REACTION, WHAT IS n?

CHARGE OF CATION OR ANION PARTICIPATING IN THE REACTION

FOR A COMPLEXATION REACTION, WHAT IS n?

NUMBER OF ELECTRON PAIRS A METAL ACCEPTS OR A LIGAND DONATES

FOR A REDOX REACTION, WHAT IS n?

NUMBER OF ELECTRONS RELEASED BY THE REDUCING AGENT OR ACCEPTED BY THE OXIDIZING AGENT

GIVEN REACTION: H2SO4 + 2NH3 -> (2NH4)+ + (SO4)2- type of reaction = ? n of acid = ? n of base = ?

type of reaction = ACID-BASE / NEUTRALIZATION n of acid (H2SO4) = 2 DONATES 2 PROTONS n of base (NH3) = 1 ACCEPTS 1 PROTON

GIVEN REACTION: Pb2+ + 2I- -> PbI2 type of reaction = ? n of Pb2+ = ? n of I- = ?

type of reaction = PRECIPITATION n of Pb2+ = 2 CHARGE OF PB2+ = 2 n of I- = 1 CHARGE OF I- = 1

GIVEN REACTION: Ag+ + 2NH3 -> Ag(NH3)2+ type of reaction = ? n of metal = ? n of ligand = ?

type of reaction = COMPLEXATION n of metal (Ag+) = 2 n of ligand (NH3) = 1

GIVEN REACTION: 2Fe3+ + Sn2+ -> Sn4+ + 2Fe2+ ``` type of reaction = ? RA = ? OA = ? n of RA = ? n of OA = ? ```

type of reaction = REDOX ``` RA = Sn2+ OA = Fe3+ ``` n of RA = 2 n of OA = 1

THESE ARE IMPORTANT IN SOLUTION PREPARATION

DILUTIONA ND ALIQUOT FACTORS

IN SOLUTION PREPARATION, KEEP IN MIND WHICH BETWEEN ______ AND ______ IS HELD CONSTANT FOR EACH PROCESS

NUMBER OF MOLES, CONCENTRATION

IN DILUTION, ______ IS KEPT CONSTANT

NUMBER OF MOLES

IN GETTING ALIQUOTS, ______ IS KEPT CONSTANT

CONCENTRATION

IMPORTANT EQUATIONS IN DILUTION

M x V = n = constant M1V1 = M2V2 = M3V3

IN GETTING ALIQUOTS, WHY IS THE NUMBER OF MOLES NOT HELD CONSTANT?

GETTING ALIQUOTS = GETTING A PORTION OF THE SOLUTION --> THIS HAS LESS MOLES THAN THE WHOLE

WHAT ARE THE STEPS IN CHEMICAL ANALYSIS?

SOPAC 1. SELECT METHOD (appropriate and reliable) 2. OBTAIN GROSS SAMPLE FROM BULK 3. PROCESS SAMPLE 4. ANALYSIS 5. CALCULATIONS AND REPORT DATA

IN SELECTING AN ANALYTICAL METHOD, IT MUST BE FIT FOR THE ______

PURPOSE

DIFFERENT SOURCES OF ANALYTICAL METHODS

BIPS 1. BOOKS (published by professional organizations_ 2. IN-HOUSE 3. PUBLISHED (in open scientific literature) 4. STANDARD ORGANIZATIONS

FACTORS IN CHOOSING A METHOD

CASES SLAPS 1. COST 2. ANALYSIS TIME 3. SAFETY 4. EQUIPMENT REQUIRED 5. SAMPLE SIZE 6. SENSITIVITY 7. LIMIT OF DETECTION 8. ACCURACY 9. PRECISION 10. SPECIFICITY AND SELECTIVIITY

FACTORS IN CHOOSING A METHOD: FUNDING SUPPORT

COST

FACTORS IN CHOOSING A METHOD: CLOSENESS TO TRUE VALUE (ABS AND REL ERROR)

ACCURACY

FACTORS IN CHOOSING A METHOD: SMALLEST CONCENTRATION THAT CAN BE DETECTED

LIMIT OF DETECTION

FACTORS IN CHOOSING A METHOD: CLOSENESS TO INDIVIDUAL DATA

PRECISION

THESE ARE USED TO EVALUATE PRECISION OF DATA

s, RSD, CONFIDENCE INTERVAL

FACTORS IN CHOOSING A METHOD: TO MINIMIZE EFFORT AND COST

ANALYSIS TIME

FACTORS IN CHOOSING A METHOD: ABILITY TO DISCRIMINATE BETWEEN ANALYTE WITH INTERFERENCES PRESENT IN THE SAMPLE MATRIX

SPECIFICITY AND SELECTIVITY

FACTORS IN CHOOSING A METHOD: CAPABILITY OF METHOD TO RESPOND RELIABLY AND MEASURABLY TO CHANGES IN ANALYTE CONCENTRATIONS

SENSITIVITY

FACTORS IN CHOOSING A METHOD: COST, AVAILABILITY

EQUIPMENT REQUIRED

FACTORS IN CHOOSING A METHOD: SINCE SOME METHODS REQUIRE LARGER AMOUNT OF SAMPLE THAN OTHERS

SAMPLE SIZE

FACTORS IN CHOOSING A METHOD: FOR THE WELFARE OF RESEARCHER/EXPERIMENTER

SAFETY

PROCESS OF SELECTING PORTION OF MATERIAL TO REPRESENT OR PROVIDE INFO ABOUT A LARGER BODY OF MATERIAL

SAMPLING

LARGER BODY OF A MATERIAL WHERE A REPRESENTATIVE SAMPLE IS TAKEN

BULK/BULK SAMPLE

PROCESS TO OBTAIN REQUIRED SAMPLE SIZE APPROPRIATE FOR ANALYSIS

SAMPLING

THIS IS DONE IN SAMPLING TO SIMPLIFY THE ANALYSIS

REDUCING SIZE OF BULK SAMPLE TO A HOMOGENOUS LAB SAMPLE

BULK SAMPLE --> GROSS SAMPLE --> LAB SAMPLE

SAMPLING

REPRESENTATIVE OF THE BULK

SAMPLE

MUST BE TAKEN INTO ACCOUNT WHEN SAMPLING

STATE OF PARENT MATERIAL

TWO TYPES OF SAMPLES

HHDS HOMOGENOUS HETEROGENOUS DYNAMIC STATIC

TYPE OF SAMPLE: BREAKFAST CEREAL

HETEROGENOUS

TYPE OF SAMPLE: VEGETABLE OIL AT 400C

HOMOGENOUS

TYPE OF SAMPLE WHEREIN THE COMPOSITION OF PARENT MATERIAL IS PERMANENT WRT SPACE AND TIME

STATIC

TYPE OF SAMPLE WHEREIN PARENT MATERIAL IS CHANGING WITH TIME

DYNAMIC

TYPE OF SAMPLE: WAREHOUSE STOCK OF FOOD, OIL IN A DRUM

STATIC

TYPE OF SAMPLE: BLOOD, RIVER WATETR

DYNAMIC

TYPE OF SAMPLE WHEREIN REMOVAL OF A PORTION OF PARENT MATERIAL AT ANY INSTANT REPRESENTS ONLY A SNAPSHOT OF THAT MOMENT IN TIME AND IN THAT PARTICULAR LOCATION

DYNAMIC

TYPES OF SAMPLING

RANDOM AND SELECTIVE

TYPES OF RANDOM SAMPLING

SSS SIMPLE STRATIFIED SYSTEMATIC

TYPE OF SAMPLING WHEREIN ANY SAMPLE HAS AN EQUAL CHANCE OF SELECTION

SIMPLE

TYPE OF SAMPLING WHEREIN LOT IS DIVIDED AND RANDOM SAMPLES ARE COLLECTED FROM EACH DIVISION

STRATIFIED

TYPE OF SAMPLING WHEREIN RANDOM WITHIN TARGET GROUPS

STRATIFIED

TYPE OF SAMPLING THAT IS BEST WHEN WHOLE POPULATION IS AVAILABLE

SIMPLE

TYPE OF SAMPLING THAT IS BEST WHEN THERE ARE SUBGROUPS TO INVESTIGATE EX: DEMOGRAPHIC GROUPINGS

STRATIFIED

TYPE OF SAMPLING WHEREIN FIRST SAMPLE IS SELECTED AT RANDOM THEN SUBSEQUENT SAMPLES ARE TAKEN ACCORDING TO A PREVIOUSLY ARRANGED INTERVAL (EVERY nth PERSON)

SYSTEMATIC

TYPE OF SAMPLING THAT IS BEST WHEN A STREAM OF REPRESENTATIVE SAMPLES ARE AVAILABLE

SYSTEMATIC

TYPE OF SAMPLING: RAFFLE DRAW

SIMPLE

TYPE OF SAMPLING: REGIONAL RAFFLE DRAWS

STRATIFIED

TYPE OF SAMPLING: TAKE EVERY 50TH BOTTLE IN A PRODUCTION LINE FOR QUALITY CONTROL ANALYSIS

SYSTEMATIC

Lecture 1: Introduction to Analytical Chemistry Flashcards

(103 cards)