C12 - Chemical Analysis 2️⃣✅ Flashcards
What is the test for hydrogen?
The test for hydrogen uses a burning splint held at the open end of a test tube of the gas
What is the positive & negative result for hydrogen?
Postitive = squeaky pop sound
Negative = no noise/ sound
What is the test for oxygen?
The test for oxygen uses a glowing splint inserted into a test tube of of gas
What is the positive & negative result for oxygen?
Positive = splint relighting when in tube (in oxygen)
Negative = splint doesnt relight
What is the test for carbon dixoide?
The test for carbon dioxide uses an aqueous solution of calcium hydroxide (lime water).
What is the positive & negative result for carbon dioxide?
Positive = When bubbled through limewater via delivery tube limewater turns milky/ cloudy
Negative = When bubbled through limewater via delivery tube limewater remains clear
What is the test for chlorine?
The test for chlorine uses litmus paper
What is the positive & negative result for chlorine?
Positive = litmus paper turns from blue to red (as chlorine gas is acidic) and then bleaches to white
Negative = litmus paper remains normal
What ions does the flame test identify?
Some positive metal ions such as Lithium, Sodium, Potassium, Calcium & Copper ions
What ions would be present if the flame colour is crimson?
Lithium ions
What ions would be present if the flame colour is yellow?
Sodium ions
What ions would be present if the flame colour is lilac?
Potassium ions
What ions would be present if the flame colour is orange-red?
Calcium ions
What ions would be present if the flame colour is green?
Copper ions
What is a precipitate?
A solid formed by a change in a solution, often due to a chemical reaction or change in temperature
What is the metal ion precipitate test used to identify?
Some positive metal ions such as Aluminium, Calcium, Magnesium, Copper (II), Iron (II) & Iron (III) ions
What ions are present if the precipitate turns white?
metal precipitate test
Aluminium, Calcium or Magnesium ions
What ions are present if the precipitate turns blue?
Copper (II) ions
What ions are present if the precipitate turns green?
Iron (II) ions
What ions are present if the precipitate turns brown?
Iron (III) ions
What 2 tests are used to indentify cations?
- Flame tests
- Metal ion precipitate test
What is the carbonate test?
When a carbonate is reacted with a dilute acid to form carbon dioxide gas to then be tested to identify the solution as a carbonate
What is the positive & negative result for the carbonate test?
Positive - solution has reacted with dilute acid and produced carbon dioxide gas which has subsequently caused the limewater to go cloudy
Negative - limewater remains clear
What is the halide test?
When halide ions in a solution produce coloured precipitates representative of halide ions when reacted with silver nitrate solution in the presence of dilute nitric acid.
What ions does the halide test identify?
Chloride, Bromide & Iodide ions
What ions would be present if the precipitate in the halide test was white?
Chloride ions
What ions would be present if the precipitate in the halide test was cream?
Bromide ions
What ions would be present if the precipitate in the halide test was yellow?
Iodide ions
What is the sulphate test?
When sulphate solutions produce a white precipitate with barium chloride solution in the presence of dilute hydrochloric acid
What is the positive & negative result for the sulphate test?
Positive = If a white precipitate was formed when solution reacted with barium chloride and dilute hydrocholoric acid
Negative = no precipitate formed
What is a pure substance?
A substance that is a single element or compound not mixed with any other substance
What is a mixture?
2 or more substances that are not chemically combined together
Pure substances melt at ____________ temperatures
Pure substances melt at specific temperatures
Mixtures melt at ____________ temperatures
Mixtures melt at a range of temperatures
What is a formulation?
A mixture that has been desgined as a useful product
Give 7 examples of formulations
- Fuels
- Cleaning agents
- Paints
- Medicines
- Alloys
- Fertilisers
- Foods
How can pure substances be distinguished from mixtures?
Because pure substances have specific metling/boiling points and mixtures have a range, data can be used to distinguish pure substacnes from mixtures
What is the equation for Rf value?
What is paper chromatography used for?
To separate the different subtances in a mixture so that they can then be identified
What does paper chromatography do?
Separate different dyes in an ink
What is this lined called for a paper chromatography experiment?
The baseline
What is the mobile phase in paper chromatography?
A substance that the molocules can move in (a liquid/gas) so in paper chromatography the solvent in bottom of beaker
What is teh stationary phase in paper chromatography?
A substance that the molocules cant move in (solid/ thick liquid) so in paper chromatography the filter paper
Substances that are soluble in solvent spend more time in the ________ phase and move up the paper at a ________ rate
Substances that are soluble in solvent spend more time in the mobile phase and move up the paper at a faster rate (therefore higher up)
Substances that are less soluble in solvent spend more time in the ________ phase and move up the paper at a ________ rate
Substances that are less soluble in solvent spend more time in the stationary phase and move up the paper at a slower rate (therefore lower down)
During paper chromatography, a mixture would ____________________ spot(s)
During paper chromatography, a mixture would separate into different spots
During paper chomatograpghy, a pure substance would ____________________ spot(s)
During paper chromatography, a pure substance would produce a single spot
What is a cation?
A positively charged ion (would go to cathode during electrolysis)
What is an anion?
A negatively charged ion (would go to anode during electrolysis)
What 3 tests are used to indentify anions?
- Carbonate test
- Halide test
- Sulphate test
What is flame emmission spectroscopy?
When metal ions are heated, emitting light with different wavelengths which are specific to that particular metal ion and can therefore be used to identify it
How is flame emmission spectroscopy more accurate than a generic flame test?
It uses a spectroscope to identify the individual wavelengths that are emitted so compounds containing multiple metals can still be identifed unlike in generic flame test when flame would just go random colour due to so many metals burning at once
What is the main advantage of flame emmission spectroscopy?
Even if a sample contains mutliple different metal ions, the spectroscope will show the wavelength lines for all of them, allowing for correct identificiation of metals
What are the 3 main benifits to instrumental methods?
- Very accurate
- Very sensitive to even tiny ammounts of a substance
- Very fast - can usually be automated (without humans)
What are the 3 drawbacks of instrumental analysis?
- Usually very expensive
- Takes specialist training to operate
- Give results that can often only be interpreted only by comparison with data from known substances to identify wavelengths etc
What is an advantage of manual tests?
- They are much cheaper than instrumental tests
What test do these results belong to? & label these results for what ions they correlate to
Flame test
What test do these results belong to? & label these results for what ions they correlate to
Metal ion precipitate test
What test do these results belong to? & label these results for what ions they correlate to
Halide test
What test uses sodium hydroxide solution?
metal ion precipitate test
What test uses a nichrome loop and a bunsen burner?
Flame test
What test uses nitric acid solution and silver nitrate solution?
Halide test
What test uses hydrochloric acid and barium chloride?
Sulphate test
What test uses limewater?
Carbonate/ carbon dixoide test
