Analytical Chemistry Chapter 2 Flashcards
(50 cards)
A standardized system of units that the scientist adopt
International System of Units (SI)
SI is the acronym of the:
“Système international d’Unités”
a non-SI unit of length that is widely used to express the wavelength of very short radiation such as x-rays.
Angstrom Unit (Å)
How to determine the amount of chemical species?
Mass Measurement
Name the Unit and Abbreviation
Mass
Length
Time
Temperature
Amount of substance
Electric current
Luminous density
kilogram - kg
Meter - m
Seconds - s
Kelvin - K
Mole - m
Ampere - A
Candela - cd
The _________ is the SI unit for the amount of a chemical substance.
It is always associated with specific microscopic entities such as atoms, molecules,
ions, electrons, other particles, or specified groups of such particles as represented by a
chemical formula.
One mole contains exactly _______elementary entities
(atoms, molecules, ions, electrons, and so on)
6.02214076×10²³ is known as _________
When expressed in the unit mol⁻¹, this number is
called _______, which is often rounded to __________
mole (mol)
6.02214076×10²³
Avogadro’s constant
Avogadro’s number
6.022×10²³ mol⁻¹
How do we calculate molar masses?
Summing the atomic masses of all the atoms appearing in a chemical formula
The ________ of a substance is the mass in grams of 1 mole of that substance.
Molar Mass (M)
______ is an
unchanging measure of the quantity of matter in an object.
_______ invariant measure of the amount of matter.
_______ is the force
of attraction between an object and its surroundings, principally Earth.
the force of gravitational attraction between that matter and earth.
Weight and mass are related by the familiar expression _________
where w is the _____,
m is its ______, and
g is the _________.
Mass
Weight
w=mg
weight of an object
mass
acceleration due to
gravity
The distinction between mass and weight is often lost in common usage, and the process of comparing masses is usually called ______.
The objects of known mass as well as the results of weighing are frequently called______.
Always bear in mind, however, that analytical data are based on _____ rather than _______.
Usage of _____ is for the act of determining the mass of an object. Also, we often say ________
to mean the standard masses used in weighing.
weighing
weights
mass, weight
weights
The masses for the elements listed in the table 2-1 (SI Base Units) are relative masses in terms of ______.
The ______ is defined as 1/12 the mass of a neutral 12C atom
unified atomic mass units (u) or daltons (Da)
dalton
The ________ is 1/1000 of a mole, and the mass in grams of a millimole,
the millimolar mass (mM), is likewise 1/1000 of the molar mass.
1 mmol = 10^-3 mol
10^3 mmol = 1 mol
millimole
There are four fundamental ways of expressing solution concentration
molar concentration percent concentration solution-diluent volume ratio
p-functions.
The ________ of a solution of a solute species X is the number of moles of that species that is contained in 1 L of the solution (not 1 L of the solvent).
molar concentration of solution of a chemical species X
symbolized by M, which has the dimensions of mol/L, or mol^-1.
Is also equal to the number of millimoles of solute per milliliter of solution.
Molar concentration or molarity
If the number moles of solute is nx, and the volume of solution is V, the molar concentration is cx, what is the equation?
Equation when finding a number of moles.
cx=nx/V
Molarity =
M= no. mol solute/no L. solution
=no. mmol solute/no mL. solution
NA = CA x VA
is the total number of moles of a solute,
regardless of its chemical state, in 1 L of solution. It describes how a
solution of a given concentration can
be prepared.
Molar analytical concentration
Gives the total number of moles of a solute in 1 L of the solution or the total number of millimoles in 1 ml.
Specifies a recipe by which the solution can be prepared.
Total number of moles of a solute, regardless of its chemical state, in one liter of solution. It describes how a solution can be prepared.
Analytical Molarity
Express the molar concentration of a particular species in a solution at equilibrium.
To determine the species molarity, it is necessary to know _________.
Molar concentration of a particular species in a solution at equilibrium.
Equilibrium Molarity
how the solute behaves when it is dissolved in a solvent
In percent concentration what are the three common method:
the denominator in each of these expressions is the ____________ rather than mass or volume of solvent
Only __________ has the advantage of being temperature independent
mass or volume of solution
weight percent
______is often used to express the concentration of commercial aqueous
reagents. For example, nitric acid is sold as a 70% (w/w) solution, meaning that the reagent contains 70 g of HNO3 per 100 g of solution.
Weight percent should more properly be called ______ and abbreviated m/m
_______ is commonly used to specify the concentration of a solution prepared by diluting a pure liquid compound with another liquid. For example, a 5% (v/v) aqueous solution of methanol usually describes a solution prepared by
diluting 5.0 mL of pure methanol with enough water to give 100 mL.
_______is often used to indicate the composition of dilute aqueous solutions of solid reagents. For example, 5% (w/v) aqueous silver nitrate often refers to a solution prepared by dissolving 5 g of silver nitrate in sufficient water
to give 100 mL of solution.
True or False: Do not always specify the type of percent when reporting
concentrations in this way
Weight percent
mass percent (weight percent is widely used in book)
Volume percent
Weight or volume percent
False
For very dilute solutions, ________ is a convenient way to express concentration:
where cppm is the ______.
For even more dilute solutions,
_______ rather than 10^6 ppm is used in the previous equation to give the results in parts per billion (ppb).
The term ______ is also used, especially in oceanography
parts per million (ppm)
(formula)
concentration in parts per million
10^9 ppb
parts per thousand (ppt)
The composition of a dilute solution is sometimes specified in terms of the volume
of a more concentrated solution and the volume of solvent used in diluting it
The volume of the former is separated from that of the latter by a _____.
Ex: 1:4 HCl
solution contains four volumes of water for each volume of concentrated hydrochloric acid.
dilution equation:
Solution-Diluent Volume Ratios
colon
Vconcd X cconcd + Vdil X cdil
Scientists frequently express the concentration of a species in terms of its _____________.
The _____ is the negative logarithm (to the base 10) of the molar concentration of that species.
___ offer the advantage of allowing concentrations that vary over 10 or more orders of magnitude to be expressed in terms of
small positive numbers.
The best-known
p-function
is _____, which is the negative
logarithm of [H3O+]
p-function, or p-value
p-value
pX = -log [X]
p-values
pH
