8 3 methods of identifying ions

A flame test is used to identify metal ions by the colour of the flame they produce when heated.

True. The Bunsen burner flame should be on a blue flame for flame tests as this is the hottest flame.

The flame colour produced by sodium ions is yellow.

The flame colour produced by copper(II) ions is green.

False. The flame colour produced by potassium ions is lilac.

The flame colour produced by calcium ions is orange-red.

False. The flame colour produced by lithium ions is crimson.

The nichrome wire is first dipped in hydrochloric acid to avoid contamination.

True. If a sample has a mixture of ions, some flame colours can be masked.

A cation is a positively charged metal ion.

The colour of the precipitate formed when sodium hydroxide is added to a solution containing copper(II) ions is blue.

False. Iron(III) ions form a brown precipitate in the presence of sodium hydroxide.

The colour of the precipitate formed by iron(II) ions in the presence of sodium hydroxide is green.

False. Ca2+ form a white precipitate in the presence of sodium hydroxide.

False. The green precipitate formed by Cr3+ ions will dissolve in excess sodium hydroxide solution to give a green solution.

The tests using sodium hydroxide to distinguish between solutions containing Al3+ ions, Ca2+ ions and Mg2+ ions:

An anion is a negatively charged ion.

The formula of a carbonate ion is CO32-.

The test for carbonate ions is:

The test and result for bromide ions is:

The test and result for iodide ions is:

True. Chloride ions give a white precipitate with silver nitrate solution.

The state symbol for the precipitate of silver bromide is s.

The formula of the precipitate formed when silver nitrate solution is added to a solution containing iodide ions is AgI.

The ionic equation for the formation of a silver bromide precipitate, including state symbols is: Ag+(aq) + Br-(aq) → AgBr (s)

Halide ions are the ions formed by elements in Group 7.

Hydrochloric acid cannot be used to acidify a sample prior to testing it for halide ions as it contains chloride ions, which would give a false positive result.

The formula of silver nitrate solution is AgNO3.

The formula of the sulfate ion is SO42-.

False. To test for sulfate ions, acidified barium chloride is used.

The white precipitate formed during a positive test for sulfate ions is barium sulfate.

The test and result for sulfate ions is:

The ionic equation for the formation of barium sulfate, including state symbols is: Ba2+ (aq) + SO42- (aq) → BaSO4 (s)

Hydrochloric acid added to a sample before barium chloride solution when testing for sulfate ions because it removes any carbonate ions which might be present and interfere with the results.

One method of instrumental analysis is flame emission spectroscopy.

Advantages of instrumental analysis over traditional methods of chemical analysis include:

Flame emission spectroscopy works by exposing the sample to a very hot flame and then measuring the intensity and wavelength of the light emitted.

Ions in unknown samples can be identified using flame emission spectroscopy by comparing the sample spectrum to reference spectra.

False. Unknown salt X does not contain rubidium ions.

True. Unknown salt X contains potassium ions

True. Unknown salt X contains three ions in total: sodium, potassium and an unknown.