Chemical Anaylsis

Question 1

What is the test for hydrogen?

Answer 1

-we remove the bung and insert a burning splint

Question 2

What is a positive test for hydrogen?

Answer 2

• will burn rapidly

- produce a pop sound

Question 3

What is the test for oxygen?

Answer 3

We add a glowing splint to the gas

Question 4

What is a positive result for oxygen?

Answer 4

Splint will relight (burst into flames)

Question 5

What is the test for carbon dioxide?

Answer 5

We use limewater- dissolved calcium hydroxide in water

• draw some gas into a plastic pipette
• bubble the gas through the lime water

Question 6

What is the result for carbon dioxide?

Answer 6

The limewater turns cloudy

Question 7

What is the test for chlorine?

Answer 7

We insert damp litmus paper into the test tube

Question 8

What is the positive result for chlorine?

Answer 8

-litmus paper is bleached white

Question 9

Describe the flame test??

Answer 9

1. We place a small amount of the chemical onto the wire mounted into a handle
2. Then we place the end of this into a blue Bunsen burner
3. The clout of the flame tells us the metal ion present

Question 10

What is the flame test result for lithium?

Answer 10

Crimson flame

Question 11

What is the flame test result for sodium?

Answer 11

Yellow flame

Question 12

What is the flame test result for potassium?

Answer 12

Lilac flame

Question 13

What is the flame test result for calcium?

Answer 13

Red/ orange flame

Question 14

What is the flame test result for copper?

Answer 14

Green flame

Question 15

What is a negative of flame tests?

Answer 15

• colour of flame test can be difficult to distinguish- especially if theres a low concentration of of the metal compound
• sometimes chemical can contain a mixture of metal ions which would mask the colour of the flame

Question 16

What kind of methods is spectroscopy?

Answer 16

Instrumental- it’s carried out by a machine

Question 17

Describe flame emission spectroscopy??

Answer 17

• a sample of the metal ion in the solution is placed into a flame
• the light given out is passed in to a machine called a spectroscope
• the spectroscope converts the lights into a line spectrum
• the position of the lines in the spectrum tells is specific for a given metal ion & can tell us the concentration of ion as the lines because more intense

Question 18

What is the advantage of instrumental methods?

Answer 18

• fast- flame spectroscopy can analyse more samples than flame tests
• sensitive- flame spectroscopy will work even on the tiniest samples
• accurate- flame spectroscopy is more likely to identify the correct metal ion than flame test

Question 19

What is your used to test for metal ions?

Answer 19

Sodium hydroxide and it forms solid precipitate of the metal hydroxide

Question 20

What is the test for copper II ions?

Answer 20

Add sodium hydroxide and it’s should form a blue precipitate

Question 21

What is the test for iron II ions?

Answer 21

Reacts with sodium hydroxide and forms a green precipitate

Question 22

What is the test for iron III ions?

Answer 22

Sodium hydroxide and it’ll form a brown precipitate

Question 23

What is the test for aluminium III?

Answer 23

Add sodium hydroxide then it’s form a clear precipitate, then add excess sodium hydroxide it’ll turn colourless

Question 24

What is the test for calcium II and magnesium?

Answer 24

Sodium hydroxide and they’ll form a white precipitate

Question 25

How do you test for carbonate ions?

Answer 25

1. Add dilute acid to the sample 2. Acid will react with the carbonate to form carbon dioxide- we see fizzing but that doesn’t prove we have carbon dioxide 3. We bubble the gas through lime water and if it goes cloudy it shows we have carbon dioxide so we started with carbon ions

Question 26

How do we test for halides ions?

Answer 26

1. We add dilute nitric acid to the samples 2. Then we add dilute sliver nitrate solutions 3. Halide ions produce a precipitate of the silver halide. Each halide makes a different colour precipitate

Question 27

What is the result for chloride ions?

Answer 27

Forms a white precipitate of silver chloride

Question 28

What is the realist for bromide ions??

Answer 28

Forms a cream precipitate of silver bromide

Question 29

What is the result for iodide ion ?

Answer 29

Produces a yellow precipitate of silver iodide

Question 30

How do we test for a sulfate ion?

Answer 30

1. Add dilute hydrochloric acid bro sample 2. Add barium chloride 3. If sulfate ions are present we see a white precipitate