What do MCL and MCLG stand for? Briefly discuss the difference between MCL and MCLG.
Prepare your answers in ONE PDF or Word file and name the file as “[] Homework#1 [YOUR NAME]“. If you wish, you may handwrite calculations clearly, take picture of them, and convert pictures into the PDF or Word file.
Show all your work and circle or highlight the final answer. It will help the TA see that you have the correct answer and actually did the work instead of just writing the correct answer.
1.(20 points) Review Toledo’s water quality report (2020) posted on the Blackboard and answer the following questions.
a.What do MCL and MCLG stand for? Briefly discuss the difference between MCL and MCLG.
b.What are three parameters representing byproducts of drinking water disinfection? Based on their MCL, which disinfection byproduct (DBP) seems to be the most toxic?
c.Microcystin is a toxin produced by harmful algal bloom. By the USEPA, what concentration (ppb) is the threshold of ‘Do Not Drink Advisory threshold’ for anyone 6 or older?
d.When Toledo water crisis occurred in year 2014, the Toledo water facility reported that microcystin levels reached 2.5 µg/L (=2.5 x 10-3mg/L). Convert 2.5 µg/L into ppb. How many times (folds) was it compared to the ‘Do Not Drink Advisory threshold’ for children 6 and under’?
2.(20 points) [Molecular/equivalent weight] Please fill the table with the values: molecular weight, valence, and equivalent weight.
| Name | Formula | Molecular weight | Valence | Equivalent weight |
| Acetate | CH3COO– | |||
| Ammonium | NH4+ | |||
| Chromate | CrO42- | |||
| Orthophosphate, dihydrogen | H2PO4– | |||
| Permanganate | MnO4– |
(Bonus 5 points)
What is the molecular weight and equivalent weight of ferric carbonate, Fe2(CO3)3?
(Hint: the valence of Fe2(CO3)3 is 6 eq/mol.)
3.(Total 20 points) [Concentration]
a.What is the molar concentration (molarity) of a 117 ppm NaCl solution?
b.126 g of potassium hydroxide, KOH, was dissolved in water to make 2 L of a solution. What is the molar concentration of KOH?
c.What is the normality of a solution containing 294 g H2SO4 in 2 L?
d.A gaseous mixture consists of 2 g of oxygen (O2), 5 g of nitrogen (N2), and 3 g of xenon (Xe). What is the mole fraction of the oxygen (O2) gas?
4.(20 points) [Dilution]
a.How much milliliters (ml) of 0.3 M KCl are needed to prepare 1.2 L of 0.05 M KCl?
b.How much water must be added to 130 ml of a 5.5 molar solution of NaOH to make a 1.2 molar solution of NaOH?
5.(20 points) [Alkalinity]
a.Calculate the “approximate” alkalinity (in mg/L as CaCO3) of water containing 5 mg/L of bicarbonate ion and 120 mg/L of carbonate ion.
b.Calculate the “exact” alkalinity of the water in problem 5b, if the pH is 9.5 at 25°C.ATTACHMENTS
