Chemical Analysis Flashcards
State the colour for the flame test of a Lithium Ion (Li+)
Crimson/red
State the colour for the flame test of a Sodium Ion (Na+)
Orange
State the colour for the flame test of a Potassium Ion (K+)
Lilac/Purple
State the colour for the flame test of a calcium ion (Ca2+)
Red
State the colour for the flame test of a Barium Ion (Ba2+)
Green
State the observation when a few drops of sodium hydroxide is added to iron (II) chloride
green precipitate/solid
State the observation when a few drops of sodium hydroxide is added to iron (III) chloride
brown precipitate/solid
State the colour for the flame test of a Lithium Ion (Li+)
Crimson/red
State the colour for the flame test of a Sodium Ion (Na+)
Orange
State the colour for the flame test of a Potassium Ion (K+)
Lilac/Purple
State the colour for the flame test of a calcium ion (Ca2+)
red
State the colour for the flame test of a Barium Ion (Ba2+)
Green
State the observation when a few drops of sodium hydroxide is added to iron (II) chloride
green precipitate/solid
State the observation when a few drops of sodium hydroxide is added to iron (III) chloride
brown precipitate/solid
State the observation when a few drops of sodium hydroxide is added to copper chloride
blue precipitate/solid
State the observation when a few drops of sodiurecipitate/solidm hydroxide is added to calcium chloride
white precipitate/solid
State the observation when a few drops of sodium hydroxide is added to magnesium chloride
white precipitate/solid
State the observation when a few drops of sodium hydroxide is added to aluminium chloride
white precipitate/solid
State the observation when an excess of sodium hydroxide is added to aluminium chloride
precipitate dissolves/disappears
Describe how to distinguish between calcium and magnesium ions
flame testcalcium ions give a red flame
Describe the test for carbonate ions
Add an acidBubblesof carbon dioxidewhich turns limewater cloudy
Describe the test for sulphate ions
Add acidified barium chloride makes a white precipitate (solid)
Describe the test for chloride ions
Add silver nitrate makes a white precipitate (solid)
Describe the test for bromide ions
Add silver nitrate makes a cream precipitate (solid)
Describe the test for iodide ions
Add silver nitrate makes a yellow precipitate
Give two advantages of using instrumental methods of analysis. [1]
faster more sensitive more accurate can detect smaller amounts
Name the precipitate made when acidified barium chloride is added to sodium sulfate
barium sulfate
BaSO4
Name the precipitate made when silver nitrate is added to potassium chloride
silver chloride
AgCl
Name the precipitate made when silver nitrate is added to potassium bromide
silver bromide
AgBr
Name the precipitate made when silver nitrate is added to potassium iodide
silver iodide
AgI
Describe the test for hydrogen
Burn it
makes a squeaky pop
Describe the test for oxygen
Relights a glowing spill
Describe the test for chlorine gas
Bleaches blue litmus paper
Describe the test for carbon dioxide
turns limewater cloudy
Explain why carbon dioxide turns limewater cloudy
Calcium hydroxide reacts with carbon dioxide to form calcium carbonate
Ca(OH)2(aq) + CO2(g) –> CaCO3(s) + H2O(l)
Describe a limitation of flame tests
Can’t analyse mixtures as one colour masks others
Describe a disadvantage of chromatography
Similar substances have similar Rf values
Needs a reference to compare to
Describe how to carry out paper chromatography
Draw a pencil line about 1cm up the paper
Place a small spot of the substance onto the paper
Suspend the paper so that the bottom just touches the solvent
Water level is above the start line
Colours would dissolve
Calcium ions
sodium ions
(note the word ion is required for the mark)
Calculate the Rf value of W
Rf = distance travelled by substance ÷ distance travelled by solvent
= 3 ÷ 10
= 0.3
(note Rf values are always less than 1)
From the chromatogram, what conclusions can the scientist make about the colourings in sweets S and P?
- S contains six / 6 colourings
- P contains five / 5 colourings
if neither of first 2 bullet points given allow 1 mark for S contains more colours than P or converse
• both S and P contain the same
five / 5 colourings
- both contain W and Y
- both sweets (may) cause hyperactivity
ignore unsafe
• neither contain X and Z
