SCHOOL SCIENCE ESSENTIALS

Take a tour of a classroom laboratory and discover how your school's scientific instruments work

- SCOTT DUTFIELD

What would a school laboratory be without an iconic Bunsen burner? These experiment staples have been around since German chemist Robert Bunsen's pioneering invention in 1855. Fed up with choking on the soot that early laboratory burners released, Bunsen created a way to control the level of oxygen from the air that mixed with the gas fuel of the burner without producing soot.

His design looked similar to the modern-day instrument, including the chimney-like barrel and all-important adjustable air holes that control the intensity of the flame emitted by the burner. The more air that enters the burner, the hotter the flame is. The Bunsen burner allowed chemists to study the different colours of flames that could be produced by heating different elements. Along with another German chemist, Gustav Kirchhoff, Bunsen made many discoveries with his new burner, such as thallium's olive-green flame and indium's indigo hue.

THE PH INSPECTOR

Since the 1300s, we've been using litmus paper to gauge the 'potential of hydrogen', or pH level, of solutions. As a chemical indicator, litmus is designed to change colour when exposed to either acidic, alkaline or neutral solutions. It does this by reacting to the presence of two different ions: acids hold positively charged hydrogen ions, whereas alkali solutions hold negatively charged hydroxide ions. When a solution is neutral, the positively and negatively charged ions balance each other out.

To make this chemical indicator, wood cellulose is infused with lichen, which contains compounds that react to the ions and change the colour of the paper. However, litmus paper can only indicate whether or not a solution is acidic or alkaline, and not to what degree.