Use a copy of the Periodic Table where you need one.
Which cation gives a white precipitate with aqueous sodium hydroxide that is insoluble in excess?
Source: Learners' Alley, Qualitative Analysis slides
A solution is acidified with dilute nitric acid, then aqueous silver nitrate is added. A yellow precipitate forms. Which ion is present?
Source: Learners' Alley, Qualitative Analysis slides
A pungent gas turns damp blue litmus paper red, then bleaches it. What is the gas?
Source: Learners' Alley, Qualitative Analysis slides
Answer these questions about qualitative analysis.
Source: Learners' Alley, Qualitative Analysis slides
When sulfur is burned, sulfur dioxide is produced. How can the identity of sulfur dioxide be confirmed?
| test | observation | |
|---|---|---|
| A | insert a glowing splint into the gas | the glowing splint rekindles |
| B | use a piece of damp blue litmus paper | blue litmus paper turns red and is then bleached |
| C | use a piece of damp red litmus paper | red litmus paper turns blue and is then bleached |
| D | use a piece of filter paper soaked with acidified potassium manganate(VII) | purple potassium manganate(VII) turns colourless |
Source: 2023 GESS Sec 3 End-of-Year P1 Q34
Separate tests were performed on an unknown solution. The results are shown in the table. What is the unknown solution?
| test | observation |
|---|---|
| add aqueous sodium hydroxide | green precipitate forms and is insoluble in excess sodium hydroxide |
| add nitric acid | no observable change |
| add aqueous sodium hydroxide, aluminium foil and warm | pungent gas evolved which turned moist red litmus paper blue |
Source: 2023 GESS Sec 3 End-of-Year P1 Q35
An excess of aqueous sodium hydroxide is added to an aqueous solution of salt X and boiled. Ammonia gas is only given off after aluminium foil is added to the hot solution. What could X be?
Source: 2024 CHS Sec 3 End-of-Year Section A Q27
There are two unlabelled test tubes. One contains aqueous ammonium nitrate and the other contains aqueous sodium nitrate. Which test could identify the solutions?
Source: 2020 SJI Year 3 End-of-Year P1 Q20
Three substances were added separately to aqueous potassium sulfate and to aqueous potassium carbonate.
1 aqueous ammonia
2 barium nitrate solution
3 dilute hydrochloric acid
Which substance(s) would give different observations with the two solutions?
Source: 2020 SJI Year 3 End-of-Year P1 Q19
A solution of compound Z reacts with sodium hydroxide solution to form a white precipitate that is insoluble in excess sodium hydroxide solution. Aluminium powder is then added. The mixture is heated and a gas that turns damp red litmus paper blue is given off. What could Z be?
Source: 2024 CHIJ Prelim P1 Q18
Aqueous ammonia is commonly used to identify cations which are present in salt solutions.
Source: 2021 SJI Prelim P2 A2(b)
Describe what you see when:
Source: 2025 TKGS Prelim P2 Q(c)