Analytical Chemistry Vocab

Front 1

aliquot

Back 1

portion

Front 2

analyte

Back 2

substances being measured

Front 3

aqueous

Back 3

a solution of anything in water

Front 4

calibration curve
OR
standard curve

Back 4

a graph of detector response as a function of analyte concentration

Front 5

composite sample

Back 5

a sample composed of multiple portions taken from different regions of a segregated heterogeneous material, which varies in composition in the same way as the material

Front 6

decant

Back 6

to pour off

Front 7

heterogeneous

Back 7

composition differs from region to region

Front 8

homogeneous

Back 8

composition is the same throughout

Front 9

interference

Back 9

occurs when a species other than the analyte increases or decreases the response of the analytical method and makes it appear that there is more or less analyte than is actually present

Front 10

masking

Back 10

the transformation of an interfering species into a form that is not detected

Front 11

qualitative analysis

Back 11

identifying what an unknown is

Front 12

quantitative analysis

Back 12

identifying how much unknown is present (analytical chemistry is concerned with this)

Front 13

quantitative transfer

Back 13

a complete transfer

Front 14

random heterogeneous material

Back 14

differences in composition occur randomly and on a fine scale

Front 15

random sample

Back 15

...is collected by taking portions from the desired number of segments chosen at random

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sample preparation

Back 16

transforming a sample into a state that is suitable for analysis

Front 17

sampling

Back 17

procuring a representative sample to measure

Front 18

segregated heterogeneous material

Back 18

large regions have obviously different compositions

Front 19

slurry

Back 19

a suspension of solid in a liquid

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species

Back 20

refers to any chemical of interest

Front 21

standard solution

Back 21

a solution containing a known concentration of a species used to generate a calibration curve

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supernatant liquid

Back 22

liquid above the packed solid

Front 23

abscissa

Back 23

the x-axis of a graph

Front 24

anhydrous

Back 24

the species does not have water in the crystal

Front 25

atomic mass

Back 25

the number of grams containing Avogadro's number of atoms

Front 26

concentration

Back 26

states how much solute is contained in a given volume or mass of solution or solvent

Front 27

density

Back 27

mass per unit volume

Front 28

electrolyte

Back 28

a substance that dissociates into ions in solution

Front 29

formal concentration

Back 29

the molarity of a strong electrolyte, emphasizes that the substance is converted into other species in solution

Front 30

formula mass

Back 30

the molecular mass of a strong electrolyte

Front 31

calorie

Back 31

the energy required to heat one gram of water from 14.5 to 15.5 degrees Celsius

Front 32

liter

Back 32

a commonly used unit for volume (the SI unit is the cubic meter) equal to 1/1000th of a cubic meter

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molality

Back 33

concentration expressed as moles of substance per kilogram of solvent (NOT total solution)

independent of temperature

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molarity

Back 34

the number of moles of a substance per liter of solution

Front 35

mole

Back 35

Avogadro's number of particles (or anything else)

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molecular mass

Back 36

the sum of atomic masses of the elements in a molecule

the number of grams containing Avogadro's number of molecules

Front 37

ordinate

Back 37

the y-axis of a graph

Front 38

ppb (parts per billion)
ppm (parts per million)

Back 38

an expression of composition that relates mass of substance to the total mass of the sample

Front 39

product

Back 39

species on the right side of a chemical equation

Front 40

reactant

Back 40

species on the left side of a chemical equation

Front 41

SI units

Back 41

Standard International units

Front 42

solute

Back 42

a minor species in a solution

Front 43

solvent

Back 43

the major species in a solution

Front 44

volume percent

Back 44

volume of solute per volume of total solution

Front 45

weight percent

Back 45

mass of solute per mass of total solution or mixture

Front 46

absorption

Back 46

the process in which a substance is taken into another

Front 47

acid wash

Back 47

replace low concentrations of cations on glassware with protons. Soak thoroughly cleaned glassware in 3-6 M HCl (in a fume hood) for >1 hour. Then, rinse well with distilled water, and soak in distilled water.

Front 48

adsorption

Back 48

the process in which a substance sticks to a surface

Front 49

ashless filter paper

Back 49

collect precipitate to be ignited, leaves little residue when burned

Front 50

buoyancy

Back 50

the upward force exerted on an object in a liquid or gaseous fluid

Front 51

buret

Back 51

a precisely manufactured glass tube with graduations enabling you to measure the volume of liquid delivered through the stopcock at the bottom

Front 52

calibration

Back 52

the process of measuring the actual quantity of mass, volume, force, electric current, etc. that corresponds to an indicated quantity on the scale of an instrument

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desiccant

Back 53

a drying agent

Front 54

desiccator

Back 54

a closed chamber containing a drying agent called a desiccator

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filtrate

Back 55

liquid that passes through the filter

Front 56

hygroscopic

Back 56

reagents which rapidly absorb moisture from the air. use procedure of weighing by difference

Front 57

ignition

Back 57

heating at high temperature over a burner or in a furnace

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meniscus

Back 58

a concave curve formed by most liquids. read volume at the bottom of meniscus using a meniscus reader

Front 59

mother liquor

Back 59

liquid from which a substance precipitates or crystallizes

Front 60

parallax

Back 60

the error that occurs when your eye is not at the same height as the liquid

Front 61

pipet

Back 61

glassware used to deliver a known volume of liquid

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tare

Back 62

the mass of an empty vessel

Front 63

volumetric flask

Back 63

glassware calibrated to contain a particular volume of solution at 20 degrees C when the bottom of the meniscus is adjusted to the center of the mark on the neck of the flask

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absolute uncertainty

Back 64

expresses the margin of uncertainty associated with a measurement

Front 65

accuracy

Back 65

describes how close a measured value is to the established "true" value

Front 66

relative uncertainty

Back 66

compares the size of the uncertainty with the size of its associated measurement

Front 67

characteristic

Back 67

a part of a logarithm, the number before the decimal point

Front 68

determinate error

Back 68

a.k.a. systematic error
arises from a flaw in equipment or design of an experiment.

in principle, systematic error can be discovered and corrected

Front 69

indeterminate error

Back 69

a.k.a. random error
arises from the effects of uncontrolled (and maybe uncontrollable) variables in the measurement

Front 70

logarithm

Back 70

the base 10 logarithm of n is the number a, whose value is such that n=10^a

Front 71

mantissa

Back 71

a part of a logarithm, the number after the decimal point.

number of digits in the mantissa of log x = number of significant figures in x

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natural logarithm

Back 72

the natural logarithm of the number x is the number y, whose value is such that x = e^y

Front 73

precision

Back 73

describes the reproducibility of a result

Front 74

standard state

Back 74

for solutes, the standard state is 1 M
for gases, the standard state is 1 bar
for solids/liquids, the standard state is the pure solid or liquid

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enthalpy change of reaction

Back 75

the heat absorbed or released when the reaction takes place under constant pressure

Front 76

exothermic

Back 76

negative enthalpy change of reaction
gives off heat

Front 77

endothermic

Back 77

positive enthalpy change of reaction
requires heat to proceed

Front 78

entropy

Back 78

measure of disorder in a substance

Front 79

Gibbs free energy

Back 79

determines whether or not a reaction will proceed
a reaction is favored if the change in gibbs free energy is negative

Front 80

Le Chậtelier's principle

Back 80

states that a changed system proceeds back to equilibrium in a manner that tries to offset the change

Front 81

reaction quotient

Back 81

similar to equilibrium constant, but evaluated at any point in a reaction. At equilibrium, the reaction quotient is equal to the equilibrium constant

Front 82

solubility product

Back 82

the equilibrium constant for a reaction in which a solid salt dissolves to give its constituent ions in solution

Front 83

saturated solution

Back 83

a solution which contains as much solid as will dissolve in solution at the given conditions

Front 84

ion pair

Back 84

a closely associated pair of ions that behaves as one species in solution

Front 85

common ion effect

Back 85

a salt will be less soluble if one of its constituent ions is already present in the solution

Front 86

coprecipitation

Back 86

when a substance whose solubility is not exceeded precipitates along with another substance

Front 87

complex ions

Back 87

consist of two or more simple ions bonded to each other

Front 88

ligand

Back 88

any atom or group of atoms attached to the species of interest

Front 89

acid

Back 89

a substance that increases the concentration of hydronium ion when added to water

Front 90

base

Back 90

a substance that decreases the concentration of hydronium ion when added to water

Front 91

salt

Back 91

any ionic solid
formally, the product of an acid-base reaction

Front 92

volumetric analysis

Back 92

procedures in which the volume of reagent needed to react with analyte are measured

Front 93

titrant

Back 93

the reagent solution used in a titration
(comes out of the buret)

Front 94

equivalence point

Back 94

occurs when the amount of titrant added is the exact amount required for stoichiometric reaction with the analyte

Front 95

end point

Back 95

a sudden change in a physical property of a solution, what we see in a titration

Front 96

indicator

Back 96

a compound with a physical property (usually color) that changes abruptly near the equivalence point

Front 97

titration error

Back 97

difference between the end point and the equivalence point (unavoidable)

Front 98

blank titration

Back 98

contains all chemicals used in the titration except analyte. subtract from measurement to determine titration error

Front 99

primary standard

Back 99

a chemical pure enough to be weighed and used directly

Front 100

standardization

Back 100

process used to determine the concentration of a titrant. the titrant is then considered a standard solution.

Front 101

direct titration

Back 101

titrant is added to analyte until the reaction is complete

Front 102

back titration

Back 102

a known excess of one standard reagent is added to the analyte. then the excess reagent is titrated with a second standard reagent

Front 103

gravimetric titration

Back 103

titrant is measured by mass, not volume

Front 104

trace analysis

Back 104

analysis of species at ppm levels or lower

Front 105

strong acid

Back 105

an acid which dissociates completely or nearly completely into its ions in solution

Front 106

hydrolysis

Back 106

refers to a reaction with water

Front 107

weak acid

Back 107

an acid that is not completely dissociated

Front 108

conjugate acid-base pair

Back 108

related by the gain or loss of a proton

Front 109

weak electrolytes

Back 109

compounds that are only partially dissociated
dissociate more as they are diluted

Front 110

buffer

Back 110

a mixture of an acid and its conjugate base
"A buffered solution resists changes in pH when acids or bases are added or when dilution occurs."