A river is contaminated with 0.65 mg/L of dichloroethylene (C2H2Cl2). What is the concentration (in ng/L) of dichloroethylene at 21°C in the air breathed by a person swimming in the river (kH for C2H2Cl2 in water is 0.033 mol/L•atm)?

The concentration of dichloroethylene in the air breather by a person swimming in the river is

Explanation:

We are given:

Concentration of dichloroethylene = 0.65 mg/L

Converting this into mol/L, we use the conversion factor:

1 g = 1000 mg

Molar mass of dichloroethylene = 97 g/mol

Converting the concentration, we get:

To calculate the pressure of the gas, we use ideal gas equation:

where,

P = pressure of the gas

C = concentration of gas =

R = Gas constant =

T = temperature of the gas =

Putting values in above equation, we get:

To calculate the concentration of gas we use the equation given by Henry's law, which is:

where,

= Henry's constant = 0.033 mol/L.atm

= molar solubility of dichloroethylene gas = ?

= partial pressure of dichloroethylene gas =

Putting values in above equation, we get:

Converting this into ng/L, we use the conversion factor:

Molar mass of dichloroethylene = 97 g/mol

Converting the concentration, we get:

Hence, the concentration of dichloroethylene in the air breather by a person swimming in the river is

the answer is d.) potassium