Quantitative Chemistry Flashcards
any chemical compound or solution used in chemical analysis
Reagent
What are the different designations of chemical purity?
- Reagent/Analytical Grade
- USP and NF Grade
- Chemically Pure/Pure Grade
- Technical/Commercial Grade
- designation that meets the specifications of the American Chemical Society
- recommended for analytical use
- ultra pure reagents
Reagent/Analytical Grade
- designation that meets the specifications of the US Pharmacopeia or the National Formulary, respectively
- indicated for impurity tolerances that not injurious to people
USP and NF Grade
True or False
the USP and NF Grade are in the interests of pharmaceutical clients and are not for chemical analysis
True
- designation that is not considered of sufficient purity for use as reagents
- impurity limitations and chemical preparations are not stated
Chemically Pure/Pure Grade
- designation that is primarily used in manufacturing and never in clinical laboratories
Technical/Commercial Grade
Reagents prepared in-house should contain the following labels:
- chemical identity
- concentration
- special handling
- storage conditions
- date prepared
- expiration date (if applicable)
- initials of technician who prepared it
solutions of a known concentration used to calculate the concentration of controls and patient specimens when performing clinical analysis
Standards
3 Types of Standards
Primary
Secondary
Reference
a highly purified chemical that can be measured directly to produce a substance of exact known concentration
Primary Standard
International Union of Pure and Applied Chemistry: degree of purity is ____
99.98%
a substance of lower purity whose concentration is determined by comparison with a primary standard
Secondary Standard
True or False
secondary standards only depend on its composition
False, also on the analytical reference method
How are secondary standards determined?
By assaying an aliquot of the solution using a primary standard for calibration
Which of the standards is most commonly used?
Secondary Standard
standards developed by the National Bureau of Standards which include substances that are difficult to purify
Reference Standards
Analogy
Fahrenheit: 32°
Celsius:
0°
Analogy
Celsius: 100°
Fahrenheit:
212°
Analogy
Kelvin: 0
Celsius:
-273°
Formula for Fahrenheit
(°C x 9/5) +32
Formula for Celsius
(°F - 32) x 5/9
Formula for converting Celsius to Kelvin
°C + 273
How is molecular weight obtained?
By adding the atomic weights of the component elements in their proper proportions
an expression of concentration wherein 1 molar solution contains 1 gram molecular weight of solute per liter solution
Molarity
the weight of an element of compound which will combine with or replace 1 gram of hydrogen
Equivalent weight
How is equivalent weight obtained?
By dividing 1 gram molecular weight of the compound by its valence
an expression of concentration wherein 1 normal contains 1 gram eq. weights per liter or mEq/mL
Normality
the ratio of concentrated solution to the total solution volume
Dilution factor
a multiple progressive dilutions ranging from more concentrated to less concentrated solutions
Serial Dilutions
When are serial dilutions useful?
- when the volume of concentrate or diluent is in short supply and needs to be minimized
- when a number of dilutions are required
Criteria to meet when serial dilution is made
- total volume desired
- amount of diluent/concentrate available
- dilution factor
- final concentration needed
- support materials required
the measurement of how much 1 ml of any liquid weighs; method of measuring density
Specific Gravity
How is specific gravity expressed?
mass/volume (g/mL)
a system established so that all quantitative measurements could be expressed in clearly defined and standardized units
International System of Units
