Identification of ions
Method overview
Use clean flame tests for selected cations, sodium hydroxide precipitates for metal ions, acid then silver nitrate for halides, acid then barium chloride for sulfate, and dilute acid plus limewater for carbonate. Record observation before inference.
Apparatus set-up
Diagramflame-test wire; Bunsen burner; sodium hydroxide; dilute nitric acid; silver nitrate; dilute hydrochloric acid; barium chloride; test tubes
Independent variable
unknown ionic compound
Dependent variable
test observations and identified ions
Control variables
reagent concentration/volume; clean apparatus; test order
Apparatus
flame-test wire; Bunsen burner; sodium hydroxide; dilute nitric acid; silver nitrate; dilute hydrochloric acid; barium chloride; test tubes
Safety
Wear eye protection; acids/alkalis irritate; silver nitrate stains; barium compounds are harmful; use small quantities.
Scientific rationale
Acidification removes interfering ions; separate sample portions avoid reagent contamination; clean wire prevents false flame colours.