3.5 - Chemical Analysis Flashcards Preview

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Flashcards in 3.5 - Chemical Analysis Deck (20)
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1
Q

What is the test for oxygen?

A

Oxygen re-lights a glowing splint

2
Q

What is the carbon dioxide test?

A

Carbon dioxide turns clear limewater milky

3
Q

How to test for ammonia gas?

A

It will change damp red litmus paper blue

4
Q

What are the colours sodium, calcium, copper and potassium in the flame tests?

A

Sodium- yellow/orange
Potassium- lilac
Calcium- brick red
Copper- green

5
Q

Describe how you would do a flame test

A
  1. Dip a clean wire loop in the acid to clean it
  2. Dip a clean wire loop in the sample solution
  3. Hold the flame test wire loop at the edge of a Bunsen flame
  4. Observe the changed colour in the flame
6
Q

Why do we add sodium hydroxide to transition metals?

A

Because their hydroxides are insoluble in water

  • if a solution of any soluble metal compound is mixed with sodium hydroxide then we get a displacement reaction. The sodium displaces a transition metal from its compound
  • a transition metal hydroxide is formed as a result
  • as it is insoluble it is a precipitate
7
Q

What colour, word and symbol equation is observed when Iron 2 reacts with sodium hydroxide?

A

-green
Iron sulfate + sodium hydroxide = iron hydroxide + sodium sulfate
FeSO4 + 2NaOH = Fe(OH)2 + Na2SO4

Fe2+ + 2OH- = Fe(OH)2

8
Q

What colour, word and symbol equation is observed when Iron 3 reacts with sodium hydroxide?

A

-red brown
Iron nitrate + sodium hydroxide = iron hydroxide + sodum nitrate
Fe(NO3)3 + 3NaOH = Fe(OH)3 + 3NaNO3
Fe2+ + 3OH- = Fe(OH)3

9
Q

What word, symbol equation and colour can be observed when reacting copper with sodium hydroxide?

A

-blue
Copper sulfate + sodium hydroxide = copper hydroxide + sodium sulfate
CuSO4 + 2NaOH = Cu(OH)2 + Na2SO4
Cu2+ + 2OH- = Cu(OH)2

10
Q

How do we test for halide (negative) ions?

A

Add dilute nitric acid to remove impurities and then silver nitrate

11
Q

What non metal corresponds with which colour precipitate?

A

Chloride - white
Bromide - cream
Iodide - yellow

12
Q

An example word, symbol and ionic equation for a halide ion

A

Sodium chloride + silver nitrate = silver chloride + sodium nitrate
AgNO3 + NaCl = AgCl + NaNO3
Ag+ + Cl- = AgCl

13
Q

How to test for a carbonate ion?

A

When an acid reacts with a carbonate then fizzing is observed
-bubbles are CO2

14
Q

How to test for a sulfate ion?

A

Add dilute hydrochloric acid followed by barium chloride

-when there is a sulfate ion then a white precipitate is seen

15
Q

How to test for an alcohol?

A
  • add oxygen so they are carboxylic acids with acidified potassium dichromate
  • solution turns green
16
Q

How to test for an alkene?

A

Add bromine water which turns from orange to colourless

17
Q

How to test for a carboxylic acid?

A

-add sodium carbonate which will fizz and turn limewater milky

18
Q

How do breathalysers work nowadays?

A

By infrared

19
Q

What can spectroscopy be used for?

A

Developing medicine

20
Q

What is the test for hydrogen?

A

If a lit splint is placed in hydrogen it will create a squeaky ‘pop’ sound