Logarithmic Scales - Questions
A logarithmic scale is used to measure the loudness of sounds with units in decibels. \(dB = 10{\log _{10}}\left( {\dfrac{{\rm{I}}}{{{{\rm{I}}_0}}}} \right)\), where \(dB\) is in decibels, \(I\) is the intensity of sound and \({{\rm{I}}_0}\) is the threshold of sound intensity detected by the human ear. How much greater is the noise intensity of a band playing at a volume of 120 dB \(\left( {{{\rm{I}}_2}} \right)\) compared with a volume level of 90 dB \(\left( {{{\rm{I}}_1}} \right)\)?
The pH of a solution is a measure of its acidity or alkalinity. Pure water has a pH of 7 and is neutral, acid has a pH < 7 and alkaline solutions have a pH > 7.
pH=\( - {\log _{10}}\left( {{{\rm{H}}^ + }} \right)\) is the pH of hydrogen ions, in moles/litre. The concentration of hydrochloric acid is \(\left[ {{{\rm{H}}^ + }} \right]\) = \({\rm{1}}{\rm{.5}} \times {\rm{1}}{{\rm{0}}^{ - 1}}\) moles/litre. The pH of hydrochloric acid is?
