Question

Question #5ae19

Answer 1

The COD is 348 mg/L.

The chemical oxygen demand (COD) is number of milligrams of oxygen needed to completely oxidize the solutes in a litre of water.

Step 1. Write the balanced equation for the combustion of formic acid.

2HCOOH + O₂ → 2CO₂ + 2H₂O

Step 2. Calculate the mass of HCOOH in 1 L of water.

`"1 L H"_2"O" × "0.100 g HCOOH"/("0.100 L H"_2"O") = "1.00 g HCOOH"`

Step 3. Calculate the mass of O₂.

`"1.00 g HCOOH" × "1 mol HCOOH"/"46.03 g HCOOH" × ("1 mol O"_2)/"2 mol HCOOH" × ("32.00 g O"_2)/("1 mol O"_2) = "0.348 g O"_2 = "348 mg O"_2`

The COD of this solution is 348 mg/L.