Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Chemistry > Chem Exam 1 > Flashcards

Chem Exam 1 Flashcards

1
Q

What are the approximate wavelengths of visible light?

A

400-700 nm

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

How does wavelength relate to energy?

A

Shorter wavelength = higher energy

Longer wavelength = lower energy

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What is the formula that relates absorbance and transmittance?

A

A = -log T = -log (T1/T0) = 2- log %T

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Examples of light sources for spectrophotometer

A

tungsten lamp, quartz-halogen lamp, deuterium discharge lamp, mercury arc lamp, or laser

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Types of monochromators

A

Colored glass filters, prism, interference filters (mirrors), diffraction grating

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What are these types of: colored glass filters, prisms, diffraction grating

A

Monochromators

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What is the measure of the monochromator’s spectral purity?

A

Bandwidth - specifically a narrow bandwidth

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What characteristics must a cuvette have in spectrophotometry?

A

Standard in size, clean, unscratched

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Types of photodetectors

A

Photocell, phototube, photomultiplier tube, diode array

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Advantages and disadvantages of a photocell as a photodetector

A

Adv: cheap, easy, does not need a current/voltage
Disadv: needs a LOT of light, quick to fatigue

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Advantages and disadvantages of a phototube as a photodetector

A

Adv: simple to use
Disadv: requires a current, requires a lot of light, cannot multiply a light signal, quick to fatigue, requires time between measurements

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Advantages and disadvantages of a photomultiplier tube

A

Adv: most sensitive of the detectors, can multiply a low light signal, slow to fatigue
Disadv: expensive and very complex

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Advantages and disadvantages of a diode array

A

Adv: can measure more than one wavelength simultaneously, specific
Disadv: not quite as sensitive as photomultiplier tube

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What are some measurements used to assure quality results from a spectrophotomer?

A

Linearity, stray light check, wavelength check

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

How can we limit background interference in spectrophotometry?

A

Sample blanking - contains everything except patient sample to detect any baseline absorption

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What are the light scattering measurements?

A

Nephelometry, turbidimetry, laser light scatter (flow cytometry)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

Nephelometry

A

Nephelometry measures the scatter of light from particles in a reaction solution with a detector for scattered light at an angle to the source light (forward scatter position)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

Turbidimetry

A

Measures the reduction in amount of light by particles in a reaction solution, can be measured with most traditional spectrophotometers

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

What is unique about the light source for A.A.S.?

A

Lamp contains the material that will be measured (heavy metals)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

What does a chopper do?

A

Chops the light signal coming from the lamp to allow for detector to distinguish between light coming from lamp and light coming from excited atoms in the flame

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

What does the monochromator do in A.A.S.?

A

Selects wavelength that reaches the detector after light enters sample
Protects the detector from large amounts of light

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

What does the detector do?

A

Distinguishes between light from the light source and light emitted by excited atoms in the flame

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

Name a few elements A.A.S. measures

A

Calcium, lead, copper, chromium, aluminum

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

Advantages of A.A.S.

A

sensitive and precise, can be used for analytes that are difficult to measure in other ways (measures heavy metals)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Disadvantages of A.A.S.
possibility for chemical interference and possibility of excitation of atoms by flame if flame temp is too high need a separate lamp for each analyte
26
What does lanthanum do?
acts as a competitor for phosphate leaving calcium free for measurement during A.A.S.
27
Limitations in calcium measurement? What is used to help with this?
calcium will frequently bind to phosphate and calcium levels will not be accurately measured. Lanthanum is added to act as a competitor for phosphate.
28
What is a fluorophore?
A substance that can fluoresce --> it absorbs energy at higher energy wavelengths and emits light at lower energy wavelength
29
What type of solution is best suited for fluorometry?
DILUTE solutions
30
What is a unique feature of a fluorometer?
It has two monochromators | Detector is at a right angle to the light source
31
Advantages of fluorometry?
Very sensitive and specific
32
Disadvantages of fluorometry?
Only useful in dilute solutions Extremely sensitive to environmental changes such as temperature, pH, light scattering, concentration quenching, and contaminating chemicals
33
What is fluorescence polarization?
A fluorometer that has the source light passed through a polarizer so all the light that reaches the sample is moving in a single plane
34
What is fluorescence polarization commonly used for?
Therapeutic drugs and drugs of abuse (compounds in low concentrations)
35
What is unique about luminometry?
There is no lamp and there is no monochromator
36
What are some advantages of luminometry?
quick assay time, easy to use and relatively simple, sensitive (low detection limits)
37
What are some disadvantages of luminometry?
Impurities can cause background noise or false signal
38
Name a unique characteristic of reflectance photometry
No water is required for testing - all components are contained in a dry slide or a dipstick
39
What is the principle behind refractometry?
As light enters liquid it will be bent from its original path - the angle at which it is bent can be related to the concentration of the liquid
40
What does an electrochemical cell consist of?
Two electrodes (reference electrode and indicator electrode) and a salt bridge
41
What is a liquid junction?
The area where two differing solutions are allowed to interact with one another. This is where a potential develops
42
What is measured in potentiometry?
The potential generated between a reference electrode and an indicator electrode. No current is applied.
43
What does ISE mean?
Ion Selective Electrode
44
What are the two types of electrodes in an ISE?
Reference and Indicator electrodes
45
What makes an ISE an ISE?
The selectivity the ISE has for a particular ion over others found in solution. The electron used is very selective for particular ions.
46
Name three common types of reference electrodes
Hydrogen Calomel (mercury/mercurous chloride) Silver/silver chloride
47
Name types of ISEs
Inert metal Metal Membrane - solid, liquid, special (gas-sensing and enzyme)
48
What does the Nernst equation describe?
The membrane potential at the surface of an ISE
49
What is the most difficult characteristic to achieve in an ISE?
Selectivity for one ion over others
50
What is the difference between direct and indirect ISE?
direct - no dilution of patient sample | indirect - dilution is made of patient sample
51
What is the assumption about "normal" plasma?
It is approximately 7% solids and 93% liquids
52
What is the electrolyte exclusion effect?
In indirect ISE, samples with higher solid content (lipemic or high protein samples) have a decreased liquid portion, but a standard amount of diluent is added. The sample is then overdiluted and can cause an inaccurate falsely decreased sodium content.
53
What is unique about an electrochemical cell that uses voltammetry?
Has 3 electrodes - reference, indicator, and auxiliary
54
What electrochemical reaction occurs in voltammetry?
Electrolysis
55
What are the two steps to anodic stripping voltammetry measurement of lead?
1. free lead is concentrated onto electrode | 2. lead is stripped off the electrode and current is measured
56
What is the difference between the potential in voltammetry vs. amperometry?
they both involve a current applied to the cell and the generated current is measured, but amperometry is always fixed potential. Amperometry is a specific type of voltammetry
57
What is an example of a coulometric measurement?
Old chloride meters
58
How does conductometry work?
Measures the changes in electrical conductivity to count the number of cells as well as gather information about size of cells
59
Is whole blood a good conductor of electricity? Plasma?
Whole blood is not a good conductor | Plasma is a good conductor and essentially an electrolyte solution
60
Where is conductometry used in the lab?
Hematology analyzers (Coulter principle)
61
What is a colligative property?
Property based solely on the number of particles in a solution (not the size/shape/chemical characteristics)
62
Identify the four colligative properties
Freezing point depression Osmotic pressure Boiling point elevation Vapor pressure depression
63
What is the colligative property most commonly used for osmolality measurement?
Freezing point depression
64
What is the difference between osmolarity and osmolality?
``` Osmolarity = number of moles solute per liter of water Osmolality = number of moles solute per kilogram of water ```
65
What substances in the plasma typically contribute to osmolality?
sodium, chloride, glucose, and urea nitrogen (BUN)
66
How do we represent chloride in the osmolality calculation?
multiply sodium by 2
67
What is osmolal gap? What does a difference greater than 10 indicate?
difference between calculated osmolality and measured osmolality A difference greater than 10 may indicate that another substance is present in the plasma that the calculation does not account for, such as alcohol or mannitol
68
What are the common uses for osmolality measurements?
Quick screen for toxic ingestion (not specific) Evaluate mannitol therapy Evaluate kidney's ability to properly concentrate urine
69
How does freezing point osmometry work?
1. solution supercooled to several degrees below freezing point by gently stirring 2. Once supercooled, stirring stops rapidly and solution freezes 3. As solution freezes, heat is released and it warms slightly to its actual freezing point 4. slush reaches a plateau, and the concentration is measured at that plateau (freezing point)
70
T/F: The more particles there are in solution, the more the freezing point is elevated.
FALSE; the freezing point is more depressed when there are more particles in a solution

Chemistry (12 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2025 Bold Learning Solutions. Terms and Conditions