5.2 Gas Tests Flashcards
How do we test for Hydrogen?
squeaky pop test
How do test for Oxygen?
glowing splint test
How do we test for Water?
anhydrous copper sulphate
What is the colour change in the chemical test for water?
white to blue
What is the physical test for water?
boiling point 100 degrees Celsius
How do we test for Carbon Dioxide?
white precipitate forms - turns cloudy
How do we test for Chlorine?
damp blue litmus paper
What is the colour change when testing for Chlorine?
blue to white (bleaches)
How do we test for Ammonia?
damp red litmus paper
What is the colour change when testing for Ammonia?
red to blue
What are cations?
positive ions
How do we test for cations?
flame test
sodium hydroxide test
ammonium test
Describe a flame test
- dip platinum wire into HCl
- dip into solution
- Bunsen flame
Why is a platinum wire used in a flame test?
does not colour the flame
Why is Hydrochloric acid used in a flame test?
clean the wire
What type of flame is used in a flame test?
non luminous Bunsen flame
What colour flame does Lithium produce?
red
Which cation produces red flame?
Lithium
What colour flame does Sodium produce?
yellow
Which cation produces yellow flame?
Sodium
What colour flame does potassium produce?
lilac
Which cation produces lilac flame?
potassium
What colour flame does calcium produce?
orange/red
Which cation produces orange/red flame?
calcium
What colour flame does copper produce?
blue/green
Which cation produces blue/green flame?
copper
Which cations use the sodium hydroxide test?
copper
iron (ii)
iron (iii)
Describe a sodium hydroxide test
- dissolve sample in water
- add NaOH
Which cation produces a blue precipitate?
copper
What colour precipitate does copper produce?
blue
Which cation produces a green precipitate?
iron (ii)
What colour precipitate does iron (ii) produce?
green
Which cation produces a brown precipitate?
iron (iii)
What colour precipitate does iron (iii) produce?
brown
Describe an ammonium test
- dissolve sample in water
- add NaOH
- damp red litmus
What is the colour change of ammonium test?
red to blue
What are anions?
negative ions
What are positive ions called?
cations
What are negative ions called?
anions
How do we test for hallides?
silver nitrate test
What does the silver nitrate test for?
hallides
Describe the silver nitrate test
- dissolve sample in water
- add nitric acid
- add silver nitrate solution
What colour precipitate does chloride produce?
white
Which hallide produces white precipitate?
chloride
What colour precipitate does bromide produce?
cream
Which hallide produces cream precipitate ?
bromide
What colour precipitate does iodide produce?
yellow
Which hallide produces yellow precipitate?
iodide
Describe a test for carbonate ions
- Add HCl
- effervescence
- limewater
Describe a test for sulfates
- add HCl
- no effervescence
- barium chloride
What is the change during the carbonate ions test?
clear -> cloudy
What is the change during the sulphate ions test?
white precipitate forms
What is the white precipitate that forms during sulphate ions test?
barium sulphate