Question

In the summer of 2016, the city of Columbus Dublin Road Water Treatment plan exceeded the regulatory level of nitrate, which is 10 ppm. What is the regulatory level concentration in:
a. mg NO3-/L
b. moles NO3-/L
c. mg-N/L

Alkaline water from a well in Owyhee County, Idaho contains carbonate (CO32-) at 24 mg/L and bicarbonate (HCO3-) at 111 mg /L. What is the total carbon concentration in mg C/L?

Answer 1

Answer:

a) $10 mg NO_3^-/L$

b) $1.61*10^{-4}mol NO_3^-/L$

c) $2.26 mg N/L$

Carbon: $C=26.64 \frac{mg C}{L}$

Explanation:

Nitrate

First of all, is important to know that:

$1 ppm=1 mg/L$

a) 10 ppm of nitrate ($NO_3^-$) is equal to $10 mg NO_3^-/L$

b) The molecular weight of nitrate is $62 g NO_3^-/mol$

$10 mg NO_3^-/L=0.01 g NO_3^-/L$

$\frac{0.01 g NO_3^-/L}{62 g NO_3^-/mol}=1.61*10^{-4} mol NO_3^-/L$

c) Nitrate has 14 mg of N per 62 mg of NO3

$10 mg NO_3^-/L*\frac{14 mg N}{62 mg NO_3^-}=2.26 mg N/L$

Carbon

Carbonate has 12 mg of C per 60 mg of $CO_3^{-2}$

Bicarbonate has 12 mg of C per 61 mg of $HCO_3^{-}$

$C=24 \frac{mg CO_3^{-2}}{L}*\frac{12 mg C}{60 mg CO_3^{-2}}+111 \frac{mg HCO_3^{-}}{L}*\frac{12 mg C}{61 mg HCO_3^{-}}$

$C=26.64 \frac{mg C}{L}$