Homework 2
ENV3001 Homework 2 1. (12 points) Identify each of the following situations as being “ethical” or “not ethical” (write a capital “E” or “N” in front of the letter of each statement, respectively). ( ) a) Students studying together to help each other learn ( ) b) One student copying homework from another ( ) c) One student peeking into another’s test paper during an exam ( ) d) Obtaining a term paper from the internet and turning it in as your own work ( ) e) Signing and sealing engineering plans done by someone else who worked under your supervision. ( ) f) Signing and sealing engineering plans done by someone else who did not work under your supervision. 2. (10 points) What is the pH of the following solution: 0.07 M HClO3 (weak acid pKA = 7.6) Page 1 of 5 ENV3001 Homework 2 3. (12 points) The weak acid hypochlorous acid (HOCl) has a pKA of 7.54 (HOCl ↔ H++OCl-). If you mix 20 g of HOCl into enough water to make 1 L of solutions, what will be the final pH? The atomic weights are H=1, O=16, Cl=35.5). 4. (10 points) The compound C7H4N3O6 burns explosively with oxygen to produce CO2, H2O, and N2. Write a balanced chemical equation for this reaction and calculate the mass of oxygen required (in grams) to burn 113 g of this compound. Page 2 of 5 ENV3001 Homework 2 5. (12 points) One method of removing phosphate from wastewater effluent is to precipitate it with aluminium sulfate (alum). A possible stoichiometry (but not exact because aluminium and phosphate can form many different chemical materials) is: 2 PO43- + Al2(SO4)3 → 2 AlPO4 + 3 SO42If the concentration of phosphate (PO43-) is 50 mg/L, how many kg of alum must be purchased annually to treat 40L/s of wastewater? How many kg/yr of solid precipitate will be formed (dry basis) if all of the phosphate is precipitated as AlPO4? 6. Calculate the pH of: a) (10 point) 0.002 molar concentration of KOH (a strong base) KOH ↔ K+ + OH¯ Page 3 of 5 ENV3001 Homework 2 b) (10 points) 0.004 molar concentration of HC2H3O2 (a weak acid, Ka = 2.5 × 10-5) HC2H3O2 ↔ H+ + C2H3O2- 7. (10 point) Calculate the equilibrium concentration (in mol/L) of metal nickel (Ni) ion in a solution made from mixing solid Ni(OH)2 in water. Ksp of = 5.5×10-16 Ni(OH)2 ↔ Ni+2 + 2OH¯ Page 4 of 5 ENV3001 Homework 2 8. (14 points) In treating an industrial wastewater, we add NaOH to remove Cr3+ ions (atomic weight) = 52). The chemical equation for the dissolution of Cr(OH)3 is Cr(OH)3 (s) ↔ Cr3+ + 3OH- (Ksp = 6.7×10-31) What is the final equilibrium concentration (in mg/L) of Cr3+ ions in a solution of Cr(OH)3 when the water has a pH of 4? Page 5 of 5
Collepals.com Plagiarism Free Papers
Are you looking for custom essay writing service or even dissertation writing services? Just request for our write my paper service, and we'll match you with the best essay writer in your subject! With an exceptional team of professional academic experts in a wide range of subjects, we can guarantee you an unrivaled quality of custom-written papers.
Get ZERO PLAGIARISM, HUMAN WRITTEN ESSAYS
Why Hire Collepals.com writers to do your paper?
Quality- We are experienced and have access to ample research materials.
We write plagiarism Free Content
Confidential- We never share or sell your personal information to third parties.
Support-Chat with us today! We are always waiting to answer all your questions.
