1. EXAM I Help Session DCC337 9-17-13 4-5 pm
ENVE-2110
EXAM I Help Session
DCC337 pm

2. Abbreviations Look through lecture notes, book and assignments
Examples: (sample test Q1)
V, w, M, L, N, n, ppm, ppb, T, p, Z, Ca, Mg, CO32-, C, HB, HA, CaCl2, acid, base, pH, pKa, KH, Creactants, k, C0, t, A, Ea, alkalinity, acidity, HCO3-, S.S., C.V., Qi, Qo, influent, effluent, r,v, MW etc.

3. UNITS Following units are considered: mg/L ppm ppb M N Molality mg/m3
Expressed as CaCO3, P, N or S

4. EXAMPLES See your notes, book and homework assignments 1 and 2:
EXAMPLE: (sample test Qs 5,6, and 7)
Q5: The concentration of trichloroethylene (TCE) is 10 ppm and the molecular weight of TCE is g/mole. Convert this to units of

5. [a] mg/L
SOLUTION:
[b]molarity

6. IDEAL GAS LAW Notes and book: Understand the equation
Be able to label all the variables and give appropriate units
Use the conversion equation between ppm and mg/m3

7. SOLUTION: EXAMPLE: (sample test Q6)
What is the carbon monoxide concentration expressed in mg/m3 of a 10 L gas mixture that contains 10-6 mole of carbon monoxide?
SOLUTION:

8. CHEMISTRY Be able to understand Matter – solid, gas, liquid
Elements – see Periodic Table
Compounds – substances made of two or more elements
Mixture
Periodic Table
Atom
Neuton
Proton
Electrons

9. Atomic weight or molecular weight
Atomic number – Z
Number of protons in nucleus
Atomic weight or molecular weight
Be able to calculate by utilizing the Periodic Table
Isotopes
Understanding what isotopes are
Be able to calculate atomic weight by utilizing isotopic mass and fractional abundance
Chemical bonds
Covalent bonds
Ionic bonds
Chemical reactions
Stoichiometry
Balancing equations/reactions
Types of reactions
Precipitation
Acid-base

10. ACID-BASE REACTIONS Acid – proton donor Base – proton acceptor
Understand terminology
Acid, base, pH, conjugate acid, conjugate base, H+, OH-, amphoteric substance, zwitter ion, pKa or Ka

11. ACID-BASE EQUILIBRIA See lecture notes and book:
Understand difference between Kw and Ka
Be able to define the equation for Ka

12. EXAMPE: (sample test Qs ,11, and 12)
Define the following compounds as acids or bases:
HCl – acid
NH3 – base
CH3OH – acid
NO3- - base

13. pH
Be able to solve simple pH calculations or solve for concentrations when pH is given (see lecture notes, HW assignments and book)
Scale 0-14
Acidic: <7
Basic: >7
Neutral: 7

14. EXAMPLE: (sample test Qs 11 and 12) Hydrochloric acid, HCl, completely ionizes when dissolved in water. Calculate the pH of the solution containing 40 mg HCl/L.

15. Calculate MW: 1+35.5=36.5 g/mole
Convert 40 mg HCl/L to moles HCl/L:
Since HCl dissociates completely in the ratio of 1 mole HCl produces 1 mole of H+, there must be 0.001M H+

16. What if the acid produces more than one H+?
You’ll have to multiply the concentration of acid by the number of moles H+ produced.
EXAMPLE: (book, HW assignment)
If 100 mg H2SO4 (MW=98 g/mole) is added to 1L of water, what is the final pH?

17. REACTION KINETICS
Be able to define zero-, first-, and second-order reaction kinetics
Understand what pseudo-first order mean
Understand the + and – sign usage:
+ produced
-consumed, decay
Be able to define the overall reaction order
Sum of orders

18. Arrhenius Equation
Know the equation, be able to define all the terms

19. BUFFERS Understand buffers and buffer capacity
Alkalinity – water’s ability to resist changes in pH on the addition of acid = acid-neutralizing capacity
Acidity – water’s ability to resist changes in pH due to addition of a base = base-neutralizing capacity

20. ALKALINITY pH < 4.5 pH 7-8 pH >12.3
Only carbonic acid present
[HO-] negligible
pH 7-8
[HCO3-] predominates over [CO3-]
[H+]=[HO-] but small compared to HCO3-
Alkalinity = [HCO3-]
pH >12.3
[H+] is negligible
[HO-] is not negligible
Alkalinity = 2[CO32-]+[HO-]
Expressed typically in (see hardness example in your notes)
mg CaCO3/L
N (eq/L)

21. MATERIAL BALANCES Understand the mass balance on mass and flow
At S.S. accumulation is zero
Understand the general mass balance equation with terms and units
See sample exam Q 10

22. BATCH REACTOR Assumptions: Well-mixed Constant volume 1-st order
Uniform composition
Constant volume
Noting in or out
1-st order
2-nd order
See sample exam Q9
Be able to recognize, draw and label

23. CSTR Assumptions: Completely mixed Able to define terms with units
Uniform concentration throughout the reactor
Water enters and leaves the reactor at a given volumetric flow rate of Q (volume/time)
Mass or quantity = CiV
Average r = r
Able to define terms with units
Be able to recognize, draw and label

24. During S.S. conditions:
See examples from sample exam – Q 2

25. PFR Assumptions: Equation: Uniform longitudinal velocity profile
Mixing is rapid enough that X-sec. can be considered well- mixed
No interaction between adjacent fluid elements in the direction of flow
Equation:
Be able to recognize, draw and label