A cool video has emerged of chemistry students showcasing their colour changing artwork created in their science class.

The footage, shot in Sydney, Australia on Wednesday, shows a portrait of a woman changing colour as it is sprayed with liquid.

Teacher Jacob Strickling explained that the student "used a fine paintbrush to apply sodium hydroxide solution to a round piece of filter paper."

"She then sprayed colourless phenolphthalein indicator onto the paper which turns pink in the presence of a base (the sodium hydroxide)," he added.