Topic 9 - Seperate Chemistry Flashcards
What colour flame would Li+ ions give off of present in the flame test for metal ions ?
Red flame
What colour flame would be given off when Na+ ions are present in sample?
Yellow
What colour would K+ give off in the flame test for metal ions?
Lilac
What colour flame would Ca2+ give off in the flame test?
Orange/red
What colour flame would be given off by Cu2+ in the flame test for metal ions ?
Blue/green
Describe the method for the flame test - for metal ions…
Firstly dip the wire loop into hydrochloride acid to remove impurities.Place loop in sample and that into outer blue flame of Bunsen burner
2 methods to test for metal ions ?
Flame test and Cation test
What colour is the precipitate formed from Al3+?
White, however it redissolves with excess NaOH to become colourless.
What colour is the precipitate of Ca2+ with NaOH?
White
What colour is the precipitate of Cu2+?
Blue precipitate
What colour is the precipitate of Fe2+?
Green precipitate
What colour is the precipitate formed from Fe3+ ?
Red or brown
Method to form a coloured precipitate ?
Take a small sample of solution and test it drop wise with sodium hydroxide(NaOH)
What do you add to form a coloured precipitate ?
Sodium Hydroxide (NaOH)
Test for Ammonium Ions ?
Add sodium hydroxide solution, then heat and test if the gas given off is the ammonia gas. We can heck that by placing a red damp Lito is paper over the gas and if it turns blue then it contains ammonium ions..
What are the anion tests ?
Tests for halide, carbonates
and sulfate ions.
What are the halide ions?
Bromide, iodide and chloride
What is the method for the halide test?
- To solution add nitric acid
- Add silver nitrate
- Watch the colour change of the precipitate
What colour is the chloride precipitate?
White
What is the chemical formula when chloride undergoes a halide year?
Ag+ + Cl- = AgBr
What colour is the precipitate of bromide after a halide test?
Cream precipitate
What is the formula of bromide precipitate after it undergoes a halide test?
Br- + Ag+ = AgBr
What is the formula of iodide after a halide test?
Ag+ + I- = AgI
What colour is the precipitate of iodide after it undergoes the halide test?
Yellow
What is the method for the Carbonate test?
- Add a dilute acid
2. If carbonates are present solution will fizz or bubble
What is the formula after a test for carbonates ?
Co2- + 2H+ = Co2 + H2O
How else can we check if carbon dioxide is given off in the carbonate test?
Use limewater , when CO2 present it will become milky
What is the method for the sulfates test?
- Add hydrochloric acid
- Add barium chloride.
- Check if the solution turns white, this means sulfates are present
Formula after the test for sulfates ?
Ba2+ + SO(4)2- = BaSo4
What is the general formula for alcohols ?
Cn + H2n+1 OH