What is a flame test used for?
Enjoying Flashcards?
Tell us what you think
What is a flame test used for?
A flame test is used to identify metal ions by the colour of the flame they produce when heated.
True or False?
The Bunsen burner flame should be on a blue flame for flame tests.
True.
The Bunsen burner flame should be on a blue flame for flame tests as this is the hottest flame.
Give the flame colour produced by sodium ions.
The flame colour produced by sodium ions is yellow.
Give the flame colour produced by copper(II) ions.
The flame colour produced by copper ions is blue -green.
True or False?
The flame colour produced by potassium ions is pink.
False.
The flame colour produced by potassium ions is lilac.
Give the flame colour produced by calcium ions.
The flame colour produced by calcium ions is orange-red.
True or False?
The flame colour produced by lithium ions is red.
True.
The flame colour produced by lithium ions is red.
Why is the nichrome wire first dipped in hydrochloric acid?
The nichrome wire is first dipped in hydrochloric acid to avoid contamination.
Define the term cation.
A cation is a positively charged ion.
What is the formula of an ammonium ion?
The formula of an ammonium ion is NH4+.
What colour precipitate is formed when sodium hydroxide is added to a solution containing copper(II) ions?
The colour of the precipitate formed when sodium hydroxide is added to a solution containing copper(II) ions is blue.
True or False?
Iron(III) ions form a green precipitate in the presence of sodium hydroxide.
False.
Iron(III) ions form a brown precipitate in the presence of sodium hydroxide.
Which two positive ions form a white precipitate when added to sodium hydroxide?
The two positive ions which form a white precipitate are Ca2+ and Al3+.
Describe a test for ammonium ions.
The test for ammonium ions is:
Add sodium hydroxide solution
If ammonium ions are present, ammonia gas is produced which turns damp red litmus paper blue.
What colour precipitate is formed when sodium hydroxide is added to a solution containing iron(II) ions??
The colour of the precipitate formed by iron(II) ions in the presence of sodium hydroxide is green.
True or False?
Ca2+ ions form a red precipitate in the presence of sodium hydroxide.
False.
Ca2+ form a white precipitate in the presence of sodium hydroxide.
Describe a test that would distinguish between Al3+ and Ca2+ ions.
A test that would distinguish between these two ions are add excess sodium hydroxide solution. The white precipitate formed by aluminium ions will dissolve in excess NaOH, but the calcium one won't
State the formula of ammonia.
The formula of ammonia is NH3.
Describe the test and result for ammonia gas using litmus paper.
The test and result for ammonia gas is that it turns damp red litmus paper blue.
True or False?
Ammonia has a pungent smell.
True.
Ammonia has a pungent smell.
True or false?
When ammonia is reacted with HCl, ammonium chloride is formed.
True.
When ammonia is reacted with HCl, ammonium chloride is formed
Give one observation that could be made when ammonia reacts with HCl.
One observation when ammonia reacts with HCl is white smoke.
Define the term anion.
An anion is a negatively charged ion.
Describe the test and result for bromide ions.
The test and result for bromide ions is:
Add dilute nitric acid followed by silver nitrate solution
A cream precipitate is formed
What is the formula of a carbonate ion?
The formula of a carbonate ion is CO32-.
Describe the test and result for carbonate ions.
The test for carbonate ions is:
Add dilute hydrochloic acid and test the gas produced by bubbling it through limewater.
If carbonate ions are present, carbon dioxide is produced which turns limewater cloudy.
Describe the test and result for iodide ions.
The test and result for iodide ions is:
Add dilute nitric acid followed by silver nitrate solution
A yellow precipitate is formed
True or False?
Chloride ions give a white precipitate with acidified silver nitrate solution.
True.
Chloride ions give a white precipitate with silver nitrate solution.
True or False?
To test for sulfate ions, acidified berylium chloride is used.
False.
To test for sulfate ions, acidified barium chloride is used
Name the white precipitate formed during a positive test for sulfate ions.
The white precipitate formed during a positive test for sulfate ions is barium sulfate.
When acidified silver nitrate solution is added to a sample containing bromide ions, a precipitate of silver bromide is formed.
What is the state symbol for this precipitate?
The state symbol for the precipitate of silver bromide is s.
Give the formula of the precipitate formed when silver nitrate solution is added to a solution containing iodide ions.
The formula of the precipitate formed when silver nitrate solution is added to a solution containing iodide ions is AgI.
Name two methods of instrumental analysis.
Methods of instrumental analysis include:
Flame Photometry.
X-ray
Infra-Red and Mass Spectroscopy
Gas Chromatography Flame Photometry
Give two advantages of instrumental analysis over traditional methods of chemical analysis.
Advantages of instrumental analysis over traditional methods of chemical analysis include:
It is faster
It is more sensitive
It is more accurate
How does flame emission spectroscopy work?
Flame emission spectroscopy works by exposing the sample to a very hot flame and then measuring the intensity and wavelength of the light emitted.
How can ions in unknown samples be identified using flame emission spectroscopy?
Ions in unknown samples can be identified using flame emission spectroscopy by comparing the sample spectrum to reference spectra.
How can flame emission spectroscopy be used to determine the concentration of metal ions in a solution?
Flame emission spectroscopy can be used to determine the concentration of metal ions in a solution by reference to a standard solution of known concentration, as the intensity of the light produced is proportional to the number of ions vaporised.