Question

If 0.025 gram of Pb(NO3)2 is dissolved in 100. grams of H2O, what is the concentration of the resulting solution, in parts per million?

Answer 1

Answer:

249.94ppm

Explanation:

Given parameters:

Mass of Pb(NO₃)₂  = 0.025g

Mass of water = 100g

Unknown:

Concentration of solution in ppm  = ?

Solution:

Concentration in parts per million gives the amount of solute found in a million units of the solution. They are desirable for expressing very small amount of solutes in a large solution. For example, the level of arsenic in the soil.

Concentration in ppm  = $\frac{amount of solute}{amount of solution} x 10^{6}$

A solution is made up of solute and solvent. The solvent here is water.

  mass of solution = mass of solute + mass of solvent = 0.025 + 100 = 100.025g

  Concentration in ppm  = $\frac{0.025}{100.025} x 10^{6}$   = 249.94ppm