Qualitative analysis Flashcards
(21 cards)
How can you test for metal ions using a flame?
Take a nichrome wire loop and dip it into hydrochloric acid and rinse in distilled water
Dip the wire in a sample of the metal compound and put the loop in a blue Bunsen flame
What colour does lithium turn in a flame test?
Red
What colour does potassium turn in a flame test?
Purple
What colour does calcium turn in a flame test?
Orange-red
How can you test for metal ions with a precipitate?
Add sodium hydroxide
What colour does copper turn in a flame test?
Blue-green
What colour does aluminium turn in the precipitate test?
White —> colourless
What colour does calcium turn in the precipitate test?
White
What colour does copper turn in the precipitate test?
Blue
What colour does iron(II) turn in the precipitate test?
Green
What colour does iron(III) turn in the precipitate test?
Brown
How do you test for ammonia?
Add sodium hydroxide and gently heat, hold a piece of damp red litmus paper over it. If ammnia is present the litmus paper will turn blue
What is the positive test for ammonia?
Damp red litmus paper turns blue
How do you test for halide ions?
Add dilute nitric acid and silver nitrate
What colour is chlorine in the halide tests?
White
What colour is bromide in the halide tests?
Cream
What colour is iodide in the halide tests?
Yellow
How do you test for carbonate ions?
Add dilute acid to make carbon dioxide and then bubble in limewater
What are the advantages of flame photometry?
Very sensitive
Very fast
Very accurate
How do you test for sulfate ions?
Add some dilute hydrochloric acid to stop any precipitation reactions occurring and then add some barium chloride solution which forms a white precipitate
What colour is sodium in a flame test?
Yellow
