Chapter EH, Problem 25R

Solution

Interpretation : The maximum limit for impurities in the copper in parts per million is to be calculated.

Concept Introduction : Chemically, copper is an element with the atomic number 29 and the letter $\text{Cu}$ . Despite being soft, copper is strong.

The maximum limit for impurities in the copper in parts per million (ppm) is $1\times {10}^{-9}\text{ppm}$ .

Copper microchips are smaller and work 25 to 30 times faster than other types of microchips as a result of the exceptionally small size of copper wires.

The purity of the copper used to create these tiny wires must be between 99.999 and 99.9999%.

The maximum impurity of copper chips is given as:

  $\begin{array}{c}\text{Impurity}=100-99.999\\ =0.001\%\end{array}$

The maximum limit for impurity in ppm is given as:

  $\begin{array}{c}\text{Impurity}\left(\text{ppm}\right)=0.001\times \frac{1}{1\times {10}^6}\left(\because 1\text{g}\text{=}\text{1}\times {\text{10}}^6\text{ppm (g)}\right)\\ =1\times {10}^{-9}\text{ppm}\end{array}$