Some BOD problems
Practice, Practice, Practice
Practice Problem #1
200 mL of Genesee river water was
collected from just below the brewery. 2
mL of river water diluted to 1 L, aerated
and seeded. The dissolved oxygen
content was 7.8 mg/L initially. After
The Ultimate BOD
A much better nickname
Example of a BOD determination
200 mL of waste water was collected, aerated
and seeded with bacteria. The dissolved
oxygen content was 7.6 mg/L initially. After 5
days, the dissolved oxygen content had
dropped to 2.
When its barely chemistry, its
What is Chemistry?
Chemistry is often defined as making and
breaking bonds; rearranging atoms to
form new substances.
There is one class of molecular reactions
that is incredibly important b
Acids & Bases in Aqueous
Hey! Theres a test
Test material ends at LAST FRIDAY!
Everything through General Equilibrium
One 8-1/2x11 inch cheat sheet with
whatever you want on it.
K is K is K is K
No matter what typ
Chemistry in Two Directions
Up until now, we have talked about reactions
as though they proceed in one direction:
from left to right, as written in a balanced
A(aq) + 2 B(aq) 6 C
In fact, this is rar
Not Cash on Delivery
Chemical Oxygen Demand
Same principle as BOD but different
Rather than biologically
decompose/oxidize organic waste, we
chemically decompose/oxidize organic
It all begins with
a balanced equation!
CnHaObNc + d Cr
Not just my nickname
What is BOD?
Biochemical Oxygen Demand
It is just what it sounds like, it is the
oxygen required by biochemical
What biochemical processes?
In the normal course of an aquatic
ecosystem, there is significant
Residual Chlorine & Chlorine
It aint chloride!
It is important to keep in mind that there is
a distinct difference between chloride ion
They are chemically distinct (Cl- vs. Cl2).
They are functionally quite different.
Chlorine and it
I cant breath in the water but the
Oxygen is one of the fundamental resources
required by life forms on Earth.
Aquatic ecosystems have a wide assortment of
Oxygen is also required for some natural
Acid/Base Properties of Salts
Hiding in plain sight
Sometimes it seems that all acids and
bases are labeled with H+ or OHRemember that a base is ANYTHING
that can accept a proton
The salt formed by the dissociation of
an acid is the conj