Question

Twenty-seven pounds (27 lb) of chlorine gas is used for treating 750,000 gal of water each day. The chlorine used up by the microorganisms in the water is measured to be 2.6 mg/L. What is the residual (excess) chlorine concentration in the treated water

Answer 1

`1.7137\ \text{mg/L}`

Step-by-step explanation:

Chlorine gas available = 27 lbs =
`27* 453.59237=12247\ \text{g}`

Amount of water used each day = 750000 gal =
`750000*3.785411784=2839058.84\ \text{L}`

Rate at which chlorine gas used = 2.6 mg/L

Chlorine gas used

`2839058.84* 2.6* 10^(-3)=7381.55\ \text{g}`

Residual content of chlorine =
`12247-7381.55=4865.45\ \text{g}`

Concentration of the residual chlorine is given by

`(4865.45)/(2839058.84)=0.0017137\ \text{g/L}=1.7137\ \text{mg/L}`

Concentration of the residual chlorine is
`1.7137\ \text{mg/L}`.