A dioxin-contaminated water source contains 0.085% dioxin by mass. How much dioxin is present in 2.5 L of this water? (Assume that the density of the solution is 1.01 g/mL.)

Solution: Here, we are going to calculate the mass of dioxin present in 2.5 L of a dioxin- contaminated water solution containing 0.085 % dioxin by mass.

Step1:

The mass percentage of a component of a solution is defined as:

Mass of the component in the solution

Mass % of a component = ----------------------------------------------------- × 100 ---(1)

Total mass of the solution

Step2:

Again, density may be defined as mass per unit volume.

Thus,

d = m / v

Here, density of the solution = 1.01 g/mL

Volume of the solution = 2.5 L = 2.5 x 1000 mL = 2500 mL [1 L = 1000 mL]

Therefore, mass of the solution = density x volume

= (1.01 g/mL) x 2500 mL

= 2525 g

Step3:

Mass % of dioxin in the solution = 0.085 %

Mass of the solution = 2525 g

Substituting the values in equation (1), we get,

0.085 = (mass of dioxin in solution / 2525 g) x 100

0.085 / 100 = mass of dioxin in solution / 2525 g

0.00085 x 2525 g = mass of dioxin in solution.

2.146 g = mass of dioxin in solution.

Thus, 2.146 g of dioxin is present in 2.5 L of a dioxin- contaminated water solution containing 0.085 % dioxin by mass.

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