Ace the IGCSE Edexcel Chemistry Challenge 2026 – Ignite Your Success!

Universal indicator changes color with how acidic or basic a solution is, reflecting the hydrogen ion concentration. As a solution becomes more basic, the color moves from green toward blue and finally purple at the highest pH. A pH of 14 is the most strongly basic end of the scale, so the indicator shows purple. Red and orange signal acidity, while blue indicates a high but not the extreme base level.