Chemical tests

Question 1

Test for alkene

Answer 1

add 2cm^3 of what you wanna test to a test tube
add 2cm^3 bromine water to the test tube
alkene-the solution will decolourise
not alkene-nothing happens

Question 2

test for haloalkanes

Answer 2

add 5 drops of unkown substance to a test tube
ass 1cm^3 of ethanol and 1cm^3 of aqeous silver nitrate
place test tube in water bath to warm it
observe precipitate

chloro-white
bromo-pale cream
iodo-pale yellow

Question 3

test for carbonates

Answer 3

-add hcl to sample
-if gas is produced, bubble through to limewater
-if limewater becomes cloudy, co2 was produced which means that carbonates were present

Question 4

test for sulfates

Answer 4

-add diliute HCl and BaCL2 solution to sample
-if white precipitate forms (barium sulfate) indication that the substance is a sulfate

Question 5

tests for halides

Answer 5

add nitric acid the silver nitrate to the solution
silver chloride is a white precipitate indicating chloring
silverbromide is a cream preicpitate indicating bromine
silver iodide is a yellow precipitate indicating iodine

Question 6

tests for ammonium compounds

Answer 6

add sodium hydroxide to substance
hold litmus paper areound the gas thats givern off
ammonia gas is alkali so the litmus paper will turn blue if ammonia is the gas therefore showing that ammonium ions are present

Question 7

what colours do the main transition elements become when mixed with NaOH

Answer 7

Cu2+ — pale blue precipitate
Fe2+ — pale green precipitate
Fe3+ — orange-brown precipitate
Mn2+ — pale brown precipitate
Cr3+ — dark green precipitate