lec Flashcards
Make up the materials we encounter everyday.
atoms
It is a particle of matter that uniquely defines a chemical element (TechTarget).
atoms
They react in simple whole number ratios form compounds
atoms
are composed of atoms of two or more elements.
compounds
Its molar mass may be determined from the atomic masses of the component atomic elements and this molar mass of the compound is numerically equal to the molecular mass
compounds
Commonly denoted as NA, is a SI defining constant with an exact value of 6.02214076x1023 reciprocal moles.
avogadro’s number
It is used as a factor in the amount of substance in a sample, defined as the number of constituent particles divided by NA.
avogadro’s number
The quantity of substance that contains the same number of ultimate particles (atoms, molecules, ions, etc.) as are contained in precisely 12.00 g of a particular isotope of carbon 12C.
mole
molar mass of a compound
molecular mass in grams
molar mass of an element
atomic mass in grams
Avogadro’s number
N = 6.02 x 10^23 particles per mole
Molar mass
grams/mole
1 molecule of C6H12O6
6 atoms C, 12 atoms H, 6 atoms O
1 mole of C6H12O6
6 moles C, 12 moles H, 6 moles O
is a homogeneous mixture of two or more substances.
solution
is the substance dissolved in a solvent and is usually present in smaller amount
solute
is the dissolving medium
solvent
components of a solution
solid, gas, liquid
solute: gas
solvent: gas
solution: ?
gas (air)
solute: gas
solvent: liquid
solution: ?
liquid (soda water, co2 in water)
solute: liquid
solvent: liquid
solution: ?
liquid (ethanol in water)
solute: gas
solvent: solid
solution: ?
solid (H2 in palladium)
solute: solid
solvent: liquid
solution: ?
liquid (salt in water)
solute: solid
solvent: solid
solution: ?
solid (bronze, brass, solder)
contains the maximum amount of a solute that will dissolve in a given solvent at a specific temperature.
saturated solution
contains less solute than it has the capacity to dissolve.
unsaturated solution
contains more solute than is present in a saturated solution.
supersaturated solution
is the ratio of the mass of a solute to the mass of the solution, multiplied by 100 percent.
percent by mass (%w/w)
Is the percent by mass of each element in a compound
percent composition by mass
is obtained by dividing the mass of each element in 1 mole of the compound by the molar mass of the compound and multiplying by 100 percent
percent composition by mass
is the simplest whole number ratio of atoms present in a compound.
empirical formula
a process in which a substance (or substances) is changed into one or more new substances
chemical reaction
uses chemical symbols to show what happens during a chemical reaction
chemical equation
the starting materials in chemical reaction
reactants
the substance formed as a result of a chemical reaction
product
diatomic elements
hydrogen (H), nitrogen (N), oxygen (O), fluorine (F), chlorine (Cl), bromine (Br), and iodine (I)
tip: Cl I H F Br O N
is the quantitative study of reactants and products in a chemical reaction.
stoichiometry
is the reactant used up first in a reaction.
limiting reagent
are the reactants present in quantities greater than necessary to react with the quantity of the limiting reagent
excess reagent
the amount of product that would result if all the limiting reagent reacted.
theoretical yield
the amount of product actually obtained from a reaction, is always less than the theoretical yield
actual yield
describes the proportion of the actual yield to the theoretical yield is the measure of how efficient a given reaction is.
percent yield
is one of the most important operations in a chemical analysis
sampling
it is the most difficult step in the entire analytical process and the step that limits the accuracy of the procedure
sampling
are used to identify chemical species, a qualitative analysis, from one that determines the amount of a constituent, a quantitative analysis
analytical methods
is the representative portion of the bulk material.
sample
the process by which a representative fraction is acquired.
sampling
a substance or chemical constituent that is of interest in an analytical procedure.
analyte
contains species that have chemical properties similar to the analyte.
sample matrix
Such species can react with the same reagents as the analyte or they can cause an instrument response that cannot be easily distinguished from the analyte
sample matrix
interference that is caused by extraneous species in the matrix.
matrix effects
Such effects can be induced not just by the sample itself but also by the reagent and the solvent used to prepare the samples.
matrix effects
macro analysis
> 0.1 g
semimicro analysis
0.01-0.1gg
micro analysis
0.0001-0.01 g
ultramicro analysis
< 0.0001 (10^-4) g
major constituent
1%-100%
minor constituent
0.01% (100 ppm) -1%
trace constituent
1 ppb to 100 ppm
ultratrace constituent
<1 ppb
The items chosen for analysis are often called
sampling units, increments, gross sample
steps in obtaining a representative sample
1) identify the population
2) collect a gross sample
3) reduce the gross sample to a lab sample
is a device which detects or measures a physical property
sensor
Sampling of metals and alloys is obtained by
sawing, milling, drilling
can often then be produced by pouring the melt into distilled
water.
granular sample
