Ch1: Chemical Concepts Flashcards
Atomic Weight
The average mass of the atoms of an element, relative to the mass of a Carbon-12 atom.
Valence
Combining power of an element, relative to that of the Hydrogen atom.
Molecular Weight
The sum of the atomic weights of the atoms that constitute a molecule.
Mole
The amount of a substance that contains the same number of elementary entities as there are atoms in exactly 12.0 grams of Carbon-12. (Avogadro’s Number)
Equivalent Weight
Weight of a compound that contains exactly 1.0 g-atom of available hydrogen or its equivalent. The definition of an “equivalent” depends on the type of reaction being considered.
EW = ______
Atomic Weight / z
Or
Molecular weight / z
“Z” depends on…
Ion charge, proton transfer, and electron transfer
ppm = ____
Mg/L / specific gravity
In the water treatment industry, it is common to express calcium, magnesium, hardness, and alkalinity concentrations in terms of…
CaCO3
Mg/L of CaCO3 =
(Mg/L of ion) x (50/equivalent wt)
meq/L =
(Mg/L) / (eq wt)
Molarity (M)
The concentration of a solution in terms of the number of miles of solute per liter of a solution (mol/L)
Normality (N)
The concentration of a solution in terms of the number of equivalents of solute per liter of solution (eq/L)
N =
zM
Ksp =
([C]^c [D]^d ) / ([A]^a [B]^b)
Ksp values must be in… (units)
Moles/ L
Solubility rules
Solvent in a dilute solution:
conc. = 1.0
Solids: conc. = 1.0
Elements in zero state: conc. = 1.0
Gases: conc. = partial pressure of gas
Rate (r) =
-k [A]^a [B]^b
Reaction order
Sum of empirically found exponents (can be a whole number or a fraction)
Reactions are regulated by…
Temperature and pressure
Zero order reaction
dC/dt = -k C^0 = -k
Ct - Co = -kt
Buffer solution
A solution that resists large changes in pH when an acid or base is added or when the solution is diluted
Low pH (5.5-8.3): Moderate pH (8.3-10.8): High pH (>10.8):
Carbonic acid - H2CO3
Bicarbonate ion - HCO3
Carbonate ion - CO3-2
Alkalinity
The measure of the capacity of a water to neutralize acids (absorbing H+ ions without a significant change in pH)
Hardness
The sum of the polyvalent metallic ions in solution (charge of +2)
Line-soda softening
The removal of dissolved minerals (hardness) from a water in order to minimize scale forming tendencies.
carbonate hardness (CH)
The portion of the total hardness that is present in the form of bicarbonate salts (with HCO3) and carbonate compounds (with CO3)
Non carbonate hardness (NCH)
The portion of the total hardness that is present in the form of non-bicarbonate salts
The volume of a sludge consists collectively of…
Dry solids volume and the water volume
