Key Analytical Chemistry Terms For Midterm

Question 1

Analyte

Answer 1

A sample’s component to be analyzed

Question 2

Accuracy

Answer 2

How close a measured value is to a ‘true’ value

Question 3

Precision

Answer 3

How close replicate measurements of analyte are to each other, how reproductive is the method

Question 4

Interference

Answer 4

When the substance that is not the Analyte is unintentionally measured by lab instrument during an experiment

Question 5

Quantitative chemical analysis

Answer 5

Any method used for determining the amount of a chemical in a sample

Question 6

Qualitative chemical analysis

Answer 6

The determination of the chemical composition of a sample

Question 7

Sampling and sample preparation

Answer 7

The mean steps for the good analytical results (results of exp. Depend on the quality of the starting material)

Question 8

Blank solution

Answer 8

Solution that contains no analyte

Question 9

Sample solution

Answer 9

Solution that is specifically prepared to analyze a sample of interest

Question 10

Standard solution

Answer 10

A solution containing an accurately known concentration

Question 11

Concentration

Answer 11

The quantity of solute present in a given quantity of solution

Question 12

Density

Answer 12

Equals the mass of the substance divided by its volume D=m/v

Question 13

Molarity

Answer 13

A unit of concentration expressed as the number of moles of dissolved solute per litre of solution

Question 14

Molality

Answer 14

Total moles of a solute contained in a kilogram of a solvent (molal concentration)

Question 15

Absolute uncertainty

Answer 15

The size of the uncertainty in a measurement

Question 16

Relative uncertainty

Answer 16

Equals the absolute error/ measured value

Question 17

Systematic error (determinate)

Answer 17

“Reproducible” inaccuracy introduced by faulty equipment or experimental design

Question 18

Random error (indeterminate)

Answer 18

Measure if fluctuation in results after repeated experimentation, equal chance of being positive, negative, magnitude varies, cannot be eliminated

Question 19

Gross errors (outliers)

Answer 19

A gross error (blunder) is generated by human mistakes or instrmental and mathematical error sources. These have to be eliminated for the reason of their large deviation; this helps the mean not to be distorted

Question 20

Propagation of uncertainty of random errors

Answer 20

Shows how uncertainty in the measurement of individual quantities translate into random variations (uncertainty) in the final result

Question 21

Certified reference material (CRMs)

Answer 21

‘Controls’ or standards used to check the quality and metrological traceability of products, to validate analytical measurement methods, or for the calibration of instruments

Question 22

Variance

Answer 22

The spread or dispersion of a set of values around the mean

Question 23

Mean

Answer 23

Average of numbers

Question 24

Sample standard deviation

Answer 24

S

Question 25

Population mean

Answer 25

U (mue)

Question 26

Population standard deviation

Answer 26

Sigma (o)

Question 27

Gaussian distribution

Answer 27

Describes the deviation of random events from central or average value

Question 28

Grubs or Q test

Answer 28

Maximum normed residual test, with s denoting the sample mean and sd respectively

Question 29

Students t test

Answer 29

A statistical test used to test weather the difference between the response of two groups is statistically significant or not

Question 30

Confidence interval

Answer 30

Presents a range of possible values within which, with some certainty, we can find the statistical measure of the population

Question 31

Standard uncertainty

Answer 31

Estimated degree of error in a measurement

Question 32

Standard deviation of the mean

Answer 32

Indicates the variability or dispersion around the mean

Question 33

F test

Answer 33

Used to compare the variance between two groups

Question 34

Degrees of freedom

Answer 34

The number of values that are free to vary

Question 35

Confidence level

Answer 35

The range of values within which the population mean is expected to lie with a certain probability

Question 36

Absorption spectrophotometry

Answer 36

An analytical chemistry tool to determine the presence of a particular substance in a sample and to quantify the amount of the substance present

Question 37

Calibration curve

Answer 37

A general method for determining the concentration of a substance in an unknown sample by comparing he unknown to a set of standard samples of known concentration

Question 38

Method of least squares

Answer 38

Assumes that the best fit curve of a given type is the curve that has minimal sum of deviations

Question 39

Dynamic range

Answer 39

The range of concentrations an instrument can read, from the minimum to the maximum detectable

Question 40

Linear range

Answer 40

The range of concentrations where the signals are directly proportional to the concentration of the Analyte in the sample

Question 41

Slope of calibration curve

Answer 41

A measure of sensitivity: how much the signal changes for a change in concentration

Question 42

Intercept of calibration curve

Answer 42

An assessment of calibration in the large

Question 43

Correlation coefficient of calibration curve

Answer 43

Very close to +1, typically 0.99 or better