cameraphone
1m glass tube (diameter about 30 mm); bungs in each end. Cotton wool soaked in conc. ammonia (care) in left-hand end, cotton wooll soaked in conc. hydrochloric acid (care) in the other end. Indicator paper strip (dry) along the inside of the tube - in this case universal indicator but litmus paper can be used. Ammonia fumes diffuse from left to right; acid fumes diffuse from right to left. The indicator paper changes colour as they move - red at the right, blue at the left. A cloud of ammonium chloride forms where the vapours meet (see insert). Takes about 15 minutes.
tip - put the ACID in first
Tags: chemistry diffusion indicator ammonia hydrochloric acid caharterhouse experiment
cameraphone
Chemistry experiment; ion migration.
Solution of copper chromate (Toxic) and cambamide (urea), green & chilled. Layer of 2M sulphuric acid on top at each end. Platinum wire electrodes in the acid. Apply current. Positively charged copper ions migrate to negative electrode (blue band), negatively charged chromate ions migrate to positive electrode (orange band). Best results in about 20 minutes.
Tags: u-tube experiment chemistry ion migration copper chromate charterhouse