Qualitative analysis Flashcards
What reagents are used to identify cations?
- sodium hydroxide
- aq ammonia
What is the effect of aqueous sodium hydroxide on calcium?
- white ppt
- insoluble in excess
What is the effect of aqueous ammonia on calcium?
- no ppt
- or very slight white ppt
What is the effect of aqueous sodium hydroxide on zinc?
- white ppt
- soluble in excess (gives colourless solution)
What is the effect of aqueous ammonia on zinc?
- white ppt
- soluble in excess (gives a colourless solution)
What is the effect of aqueous sodium hydroxide on aluminium?
- white ppt
- soluble in excess (gives colourless solution)
What is the effect of aqueous ammonia on aluminium?
- white ppt
- insoluble in excess
What is the effect of aqueous sodium hydroxide on lead?
- white ppt
- soluble in excess (gives colourless solution)
What is the effect of aqueous ammonia on lead?
- white ppt
- insoluble in excess
What is the effect of aqueous sodium hydroxide on copper (ll)?
- light blue ppt
- insoluble in excess
What is the effect of aqueous ammonia on copper (ll)?
- light blue ppt
- soluble in excess (gives a dark blue solution)
What is the effect of aqueous sodium hydroxide on iron (ll)?
- green ppt
- insoluble in excess
What is the effect of aqueous ammonia on iron (ll)?
- green ppt
- insoluble in excess
What is the effect of aqueous sodium hydroxide on iron (lll)?
- red-brown ppt
- insoluble in excess
What is the effect of aqueous ammonia on iron (lll)?
- red-brown ppt
- insoluble in excess
What is the effect of aqueous sodium hydroxide on ammonium?
- ammonia produced upon warming
How does one differentiate between lead and aluminum ions?
- add potassium iodide
- in lead ion is present, bright yellow ppt of lead (ll) iodide will be observed
- if aluminium is present, no visible change occurs
What is another way to differentiate between lead and aluminium ions other than adding potassium iodide?
- add dilute HCl
- if lead ion is present, a white ppt or PbCl2 will be observed
- if aluminium ion is present, no visible change occurs
How does one identify a carbonate ion?
- add dilute acid
- if carbonate ion is present, effervescence will be observed
- gas forms white ppt in limewater
- carbon dioxide is produced
How does one identify a chloride ion?
- acidify with dilute nitric acid
- then add aq silver nitrate
- if chloride ion is present, a white ppt is formed (silver chloride)
How does one identify an iodide ion? (1 of 2 ways)
- acidify with dilute nitric acid
- add aq silver nitrate
- if iodide ion is present, a yellow ppt is formed
How does one identify an iodide ion (2 of 2 ways)
- acidify with dilute nitric acid
- add aq lead (ll) nitrate
- if iodide ion is present,
a bright yellow ppt is formed
How does one identify a nitrate ion?
- add aq sodium hydroxide
- then aluminium foil
- warm
- if nitrate ion is present, effervescence is observed
- moist red litmus turns blue (ammonia produced)
How does one identify a sulfate ion?
- acidify with dilute nitric acid
- add aq barium nitrate
- if sulfate ion is present, white ppt is formed
How does one test for ammonia?
- place a damp piece of red litmus paper near the mouth of the test tube containing the gas
- ammonia gas turns damp red litmus paper blue
How does one describe ammonia?
- colourless
- pungent gas
How does one test for carbon dioxide?
- bubble the gas into lime water
- carbon dioxide gas forms a white ppt of CaCO3 with limewater
How does one describe carbon dioxide?
- colourless
- odorless gas