Question

Homework 5-Feb 28.docx Please prepare your homework answers either in WORD file or on an engineering paper by handwriting. If you use a handwriting form, please scan the paper neatly and upload a PDF or word version to Canvas and HAND in your original hard copy to me before the class if possible. NOTE: This homework contains a submission of an excel file in addition to your WORD or PDF file Again, no late homework is accepted. No exceptions. Size 298 Solutions to Homework 2 View (1) The phenol concentration in a water solution is 20 ppm and the density of this solution is 1.1 g/cm. Please express the concentration by mg/L. (2) Chlorine dioxide (CIO) is added to the water pipeline as a predisinfection measure similar to Ozonation as we discussed in the class. CIO, reacts with organics and pathogens and follows first- order reaction kinetics. The concentration of CIO decreases to half of the initial level within 20 min. If we want to maintain the final concentration of CIO, at 10 mg/L at the pipe's exit into the plant as shown below, what is the initial CIO) concentration that should be spiked into the water pipeline? The pipe has the dimension shown in the following graph.

Answer 1

solution 1:
Mass of 1 litre solution= 1.1g/cm3 x 1000cm3/L

= 1100g/L

therefore.... 20 ppm of 1100g = 1100g x 10-6

  = 1.1 x 10-3 g

= 1.1 mg concentration in mg/L

= 1.1mg/L **Ans = 1.1 mg/L