engineering

[shay]

this is my mid term and idk how to do any of these problems. i know it says dont give answers but can you at least show me examples of how to do these equations because i have no clue

 

1) A 500 ml aqueous solution contains 0.005 mg of arsenic. What is the concentration of arsenic in terms of ppb?

 

 

 

 

 

2) How many feet of water (depth) are in an open reservoir 80 ft. in diameter if the pressure at the bottom outlet is 50psi?

 

 

 

 

 

3) What is the detention time of a settling tank with a 40 ft. diameter and a side water depth of 15 ft. with a flow of 10,000 gpd ?

 

 

 

4) Determine the BOD 5 for the following.

 

Initial DO = 9.6 mg/L

 

5 Day DO = 4.3 mg/L

 

Sample Volume = 5 mL

 

 

 

 

 

5) What is the hydrostatic pressure at a customer’s tap located 110ft above the main when

 

the pressure in the water main is 80 psi?

 

 

 

6) Determine the TDS for the following.

 

Clean filter weight = 455 mg

 

Filtered weight = 515 mg

 

After ignition weight = 495 mg

 

Sample size = 100mL

 

 

 

7) What would the total expected daily water demand be for a small town of 18,750 people? (express in mgd)

[hypervalent_iodine]

As per your other thread and as you have noted, we can't simply give you the answers. Tell us what you have done, even if it's nothing, and what you are having trouble with and we'll go from there for you

 

Starting with the first question, is there anything specifically you don't get? Do you know what units ppb or ppm are in?

 

As a side note, I saw this comment in the other thread:

 

1) Turn both the liquid and weight amounts to Moles then times by avogadro's number before dividing the number of arsenic molecules by the number of water ones and changing to the correct units.

 

This isn't how you calculate ppb.

Edited October 14, 2011 by hypervalent_iodine

[swansont]

!

Moderator Note

No, we won't do your midterm for you. Don't repost this again.