Flashcards in C3.4 Acids, ions, and metals Deck (14):
What can a flame test be used for?
To detect the presence of a metal ion in a compound
How do you complete a flame test?
Dip a clean loop in the sample solution
Hold the flame test in the bunsen burner flame
Observe the colour of the flame
How do you test for positive ions ( cations )
eg SODIUM bromide
-Dissolve a small amount in water
-Add sodium hydroxide solution
- Identify the colour of the precipitate formed
If there is a WHITE precipitate, add MORE sodium hydroxide, If the precipitate does not dissolve, DO A FLAME TEST
What colour precipitate does iron II form
What cation forms a red/brown precipitate?
How can you identify copper?
What colour flames do Lithium, Magnesium, and Sodium produce?
Lithium = Red
Magnesium = No colour
Sodium = Yellow
Which cations would lilac or brick red flames indicate?
Lilac = potassium
Brick red = calcium
How do you test for negative ions (anions)?
-Dissolve in water
- Add Hydrochloric acid
If A gas is given off = CARBONATE
If no gas is given off ....
-Add hydrochloric acid + Barium chloride
If a white precipitate is formed = SULPHATE
-Add nitric acid and silver nitrate to fresh solution
identify the colour precipitate formed
What ion is present when a white precipitate is formed?
How do you identify a BROMIDE ion
Forms a CREAM precipitate with nitric acid and silver nitrate
What ion is present when a YELLOW precipitate is formed?
How are titrations used to identify the acidity of a solution?
Titrations can be used to determine the volume of acid and alkali needed to react together to produce a neutral solution