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ENVE-2110

ENVE-2110. EXAM I Help Session DCC337 9-17-13 4-5 pm. Abbreviations. Look through lecture notes, book and assignments Examples: (sample test Q1)

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ENVE-2110

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  1. ENVE-2110 EXAM I Help Session DCC337 9-17-13 4-5 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 131.5 g/mole. Convert this to units of

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

  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. 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 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 • 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 • 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 • 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: • 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

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