(Done) Chemical Analysis (Paper 2) Flashcards
1
Q
Define a pure substance
A
- A substance that only contains one compound or element
2
Q
How can you test the purity of a substance
A
- Comparing the melting and boiling point of the substance to the melting and boiling point of a pure substance
3
Q
Define Solvent
A
- The liquid in which a substance dissolves to form a solution
4
Q
Define formulations
A
- Useful mixtures with a precise purpose that are made by following a formula
5
Q
Features of the ingredients of formulations
A
- Each component in a formulation is present in a measured quantity and contributes to the properties of the formulation so it meets its required function
6
Q
Why is chromatography used as a separation technique
A
- It allows us to separate substances based on their solubilities
7
Q
Define the stationary phase in chromatography
A
- The part were the molecules cannot move
8
Q
Define the mobile phase in chromatography
A
- The part where the molecules can move
9
Q
What result does a pure compound produce in chromatography
A
- A single spot in all solvents
10
Q
What result do compounds in a mixture produce in chromatography
A
- May separate into different spots depending on the solvent
11
Q
Why is the start line drawn in pencil in chromatography
A
- If the line was drawn in pen, the ink would move up the paper with the solvent
12
Q
Calculation for Rf value of a substance in chromatography
A
- Distance travelled by substance (B) / Distance travelled by solvent (A)
13
Q
What is the test for chlorine gas and a positive result
A
- Place damp litmus paper in a test tube containing the gas being tested
- If chlorine gas is present, the litmus paper will be bleached white as chlorine is acidic
14
Q
What is the test for oxygen and a positive result
A
- Place a glowing splint inside a test tube containing
- If oxygen is present, the splint will relight
15
Q
What is the test for carbon dioxide
A
- Bubbling the gas being tested through a limewater solution
- If carbon dioxide is present, the limewater will turn cloudy
16
Q
What is the test for hydrogen
A
- Hold a lit splint at the open end of a test tube containing the gas being tested
- If hydrogen is present, you will hear a squeaky pop
17
Q
What is the test for carbonates and a positive result
A
- Add a couple drops of dilute acid to a test tube containing the solution being tested
- Connect this test tube to a test tube containing limewater
- If carbonate ions are present, carbon dioxide will be released and will turn the limewater cloudy when it bubbles through it
18
Q
What is the test for sulphate ions and a positive result
A
- Add a couple drops of dilute hydrochloric acid, followed by a couple drops of barium chloride solution to a test tube containing the solution being tested
- If sulphate ions are present, a white precipitate of barium sulphate will form
19
Q
What is the test for halide ions
A
- Add a couple drops of dilute nitric acid, followed by a couple drops of silver nitrate solution to a test tube containing the solution being tested
20
Q
What is a positive halide test result for chloride
A
- White precipitate of silver chloride
21
Q
What is a positive halide test result for bromide
A
- Cream precipitate of silver bromide
22
Q
What is a positive halide result for iodide
A
- Yellow precipitate of silver iodide
23
Q
What colour does lithium burn
A
- Crimson
24
Q
What colour does sodium burn
A
- Yellow
25
What colour does potassium burn
- Lilac
26
What colour does calcium burn
- Orange-red
27
What colour does copper burn
- Green
28
What is the test for calcium ions in a solution
- Add a few drops of sodium hydroxide solution
- White precipitate
29
What is the test for copper ions in a solution
- Add a few drops of sodium hydroxide solution
- Blue precipitate
30
What is the test for Iron (II) ions in a solution
- Add a few drops of sodium hydroxide solution
- Green precipitate
31
What is the test for Iron (III) ions in a solution
- Add a few drops of sodium hydroxide solution
- Brown precipitate
32
What is the test for aluminium ions in a solution
- Add a few drops of sodium hydroxide solution
- White precipitate but redissolves to become colourless
33
What is the test for magnesium ions in a solution
- Add a few drops of sodium hydroxide solution
- White precipitate
34
How does flame emission spectroscopy work
- A sample is placed in a flame
- As the ions heat up, their electrons become excited
- When the electrons drop back down to their original energy levels, they transfer energy as light
- The light passes through a spectroscope, which can detect different wavelengths of light to produce a line spectrum
35
How does flame emission spectroscopy identify ions
- The combination of wavelengths emitted by an ion depend on its charge and its electron arrangement
- Since no two ions have the same charge and electron arrangement, different ions emit different wavelengths of light
- So each ion produces a different pattern of wavelengths and has a different line spectrum
36
What does the intensity of the line spectrum in flame emission spectroscopy indicate
- The concentration of that ion in the solution
37
Define instrumental analysis
- Tests that use machines
38
What are the advantages of using instrumental analysis
- Very sensitive
- Very fast and can be automated
- Very accurate
