Topic 1 - Qualitative Analysis Flashcards
What is qualitative analysis?
- Tells you what is present
- Allows you to tell if a particular substance is present
When might a qualitative analysis be used?
-To detect if there is a poisonous substance in drinking water
What is quantitative analysis?
-Tells you how much is present
When might quantitative analysis be used?
-Suspected drink-drivers to see how much alcohol in blood
How do you test for positive ions using sodium hydroxide?
- Many metal hydroxides are insoluble, precipitate out of solution when formed. Some of these hydroxides have characteristic colours
- Add sodium hydroxide solution to solution of mystery compound
- Can use the colour of the insoluble hydroxide formed to see which metal was in the compound
When the precipitate test is done, what colour precipitate does calcium [2+] form and what is the equation for this reaction?
When the precipitate test is done, what colour precipitate does copper (II) [2+] form and what is the equation for this reaction?
When the precipitate test is done, what colour precipitate does iron (II) [2+] form and what is the equation for this reaction?
When the precipitate test is done, what colour precipitate does iron (III) [3+] form and what is the equation for this reaction?
When the precipitate test is done, what colour precipitate does aluminium [3+] form and what is the equation for this reaction?
When the precipitate test is done, what colour precipitate does ammonium (NH4) [+] form?
No precipitate formed but heat given off as ammonia
How can you identify ammonia gas?
-Turns Universal indicator paper purple
-Turns damp red litmus paper blue
(-Also has a distinct smell)
How would you test for a halide using nitric acid and silver nitrate?
- Add dilute nitric acid HNO3 to the halide solution (forms a nitrate and hydrochloric acid)
- Add silver nitrate AgNO3 to form nitric acid, silver and a halogen
- The silver and the halogen react forming a precipitate
When the test for halides is done, what colour precipitate does chlorine form and what is the equation for the final reaction in the test?
When the test for halides is done, what colour precipitate does bromiene form and what is the equation for the final reaction in the test?
When the test for halides is done, what colour precipitate does iodine form and what is the equation for the final reaction in the test?
What colour flame does sodium Na[+] form in the flame test?
yellow/orange
What colour flame does potassium K[2+] form in the flame test?
lilac
What colour flame does copper Cu [+] form in the flame test?
blue-green
What colour flame does calcium Ca[2+] form in the flame test?
brick-red
How do you test for carbonates?
- Add dilute acid which gives off CO2 if it is a carbonate
- CO2 turns limewater cloudy/milky
How do you test for sulphates?
- Add hydrochloric acid and barium chloride
- Forms a white precipitate of barium sulphate