Question

1. copper is an element that is required in very small concentrations in the bodies if animals. what is the concentration of copper, in parts per million, if 1.0l of drinking water contains 3.0×10⁻⁵g of copper. (ans. 0.030ppm) 5. formaldehyde is an indoor air pollutant that comes from synthetic materials and cigarette smokes. a dangerous

Explanation:

Step1: Recall ppm formula for dilute solutions

For dilute aqueous solutions, the density of water is approximately \(1\space g/mL\), so \(1.0\space L\) of water has a mass of \(1000\space g\) (since \(1\space L = 1000\space mL\) and density \(
ho=\frac{m}{V}\), \(m=
ho V = 1\space g/mL\times1000\space mL = 1000\space g\)). Parts per million (ppm) for a solute in a solution is defined as \(\text{ppm}=\frac{\text{mass of solute}}{\text{mass of solution}}\times10^{6}\) (when the solution is dilute, mass of solution \(\approx\) mass of solvent, here water).

Step2: Identify mass of solute and solution

Mass of copper (solute) \(m_{solute}=3.0\times 10^{-5}\space g\)
Mass of water (solution, since it's dilute) \(m_{solution}=1.0\space L\times1000\space g/L = 1000\space g\) (because density of water is \(1\space g/mL\) or \(1000\space g/L\))

Step3: Calculate ppm

Using the formula \(\text{ppm}=\frac{m_{solute}}{m_{solution}}\times 10^{6}\)
Substitute the values: \(\text{ppm}=\frac{3.0\times 10^{-5}\space g}{1000\space g}\times 10^{6}\)
First, simplify \(\frac{10^{6}}{1000}=10^{3}\)
Then, \(\text{ppm}=3.0\times 10^{-5}\times 10^{3}=3.0\times 10^{-2}= 0.030\space ppm\)

Answer:

\(0.030\space ppm\)