Question

1. if a mass of 56.2 g of mercury is dissolved in 25 kg of water, what is the concentration of mercury in ppm?

Explanation:

Step1: Convert mass units

Convert \(25\ kg\) of water to grams. Since \(1\ kg = 1000\ g\), then \(25\ kg=25\times1000 = 25000\ g\).

Step2: Calculate mass of solution

Assume the mass of mercury (\(m_{Hg}=56.2\ g\)) and the mass of water (\(m_{water} = 25000\ g\)). The mass of the solution \(m_{solution}\approx m_{water}\) (because \(m_{Hg}\ll m_{water}\), mercury is a solute and water is a solvent, and in dilute solutions, \(m_{solution}\approx m_{solvent}\)).

Step3: Use ppm formula

The formula for parts - per - million (ppm) is \(ppm=\frac{m_{solute}}{m_{solution}}\times10^{6}\). Substitute \(m_{solute}=56.2\ g\) and \(m_{solution} = 25000\ g\) into the formula: \(ppm=\frac{56.2}{25000}\times10^{6}\).

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Answer:

\(2248\ ppm\)