Lecture 1

Question 1

Accuracy

Answer 1

agreement of a measure value with an accepted value (target)

Question 2

Precision

Answer 2

onsistency of a measurement made in different trials/ runs

Question 3

Mean

Answer 3

Average
Add all values up then divide by how many units added

Question 4

SD (Standard Deviation)

Answer 4

When there is a value above or below the mean
calculated based off of the mean and the number of units in the sampling

Question 5

Standard deviation: Formulation

Answer 5

s= square root of E (x-xi)^2/n-1

Question 6

Histograms

Answer 6

Frequency vs outcome

Question 7

Frequency and outcome

Answer 7

Frequency - how often an outcome happened, on y axis
Outcomes - what happened, - on x axis

Question 8

Bell-shaped curves

Answer 8

Many histograms have a profile that looks like a bell-shaped curve as
smaller bin sizes
large number samples

Question 9

1-3 Standard deviation

Answer 9

63.8% confident = 1 SD
95.5% confident = 2 SD
99.7% confident= 3 SD

Question 10

Does averaging improve data?

Answer 10

Yes, as number of measurements (n) gets larger the range at any confidence gets smaller

Question 11

Coefficient of variation (CV)

Answer 11

Formula: CV= SD/Mean *100
expresses error as %
range at any confidence will be different for every type measurement

Question 12

What is CV known as?

Answer 12

referred to as “the index of precision”

Question 13

Spectrophotometry

Answer 13

Often used to determine concentrations - >less light-> higher concentration
Shining light through sample and seeing how much light gets through

Question 14

Visible light

Answer 14

Most common light used is visible to our eyes

Question 15

What is the frequency range of visible light?

Answer 15

400-700 nm

Question 16

Wavelengths

Answer 16

distance between high points

Question 17

Which types of light aren’t seen?

Answer 17

UltraViolet (UV) and Infrared (IR) light

Question 18

Transmittance formula

Answer 18

I/Io *100= transmittance T

Question 19

Transmittance: Io

Answer 19

(reference/background) measured first - solvent alone

Question 20

Transmittance: I

Answer 20

amount of light that gets through when the sample + solvent is in the light beam

Question 21

Transmittance

Answer 21

fraction light that got through

Question 22

Monochromators

Answer 22

Separate light into narrow range of wavelength (colors)

Question 23

What types of monochromators are they

Answer 23

3 types:
Prism, refraction grating, and light filters

Question 24

Single Beam Spectrophotometer parts

Answer 24

Source
Monochromator
Slit before sample
Slit after sample
Detector

Question 25

Single Beam Spectrophotometer: Source

Answer 25

Provides sufficient light
Tungsten Lamp is common source

Question 26

Single Beam Spectrophotometer: Monochromator

Answer 26

Accepts polychromatic input light from a lamp and outputs monochromatic light

Question 27

Single Beam Spectrophotometer: Prism

Answer 27

used to isolate different wavelengths

Question 28

Single Beam Spectrophotometer: Filter

Answer 28

Separates different parts of the electromagnetic spectrum by absorbing or reflecting certain wavelengths and transmitting other wavelengths

Question 29

Single Beam Spectrophotometer: Diffraction grating

Answer 29

an optical component with a regular pattern, which splits (diffracts) light into several different beams traveling in different directions

Question 30

Single Beam Spectrophotometer: Cuvettes

Answer 30

Chosen for transparency in the spectral wavelengths of interest

Question 31

Plants Formula

Answer 31

Energy of each one photon of light

Question 32

Planck’s constant

Answer 32

h = 6.62 x 10-34 J*s

Question 33

Beers law

Answer 33

A = ebc

Question 34

Beers law: Components

Answer 34

e = is the Molar Absorptivity aka Molar Extinction Coefficient
b is the pathlength - the distance the light travels through the sample
c is the concentration, usually in moles/liter (M)
A = Absorbance = –log(I/Io)