2(h) Chemical tests Flashcards
test for group 7 - ions?
add dilute nitric acid and silver nitrate:
chlorine: white
bromide: cream
iodide: pale yellow
flame test process?
- dip the loop (composed of an unreactive metal) in concentrated acid and then hold it in the blue flame until no colour change (cleans the fire to avoid contamination).
- dip the loop in the solid sample and place it in the edge of the blue Bunsen flame
- avoid letting the wire get so hot that it glows red otherwise this can be confused with a flame colour
why do you clean the wire with a concentrated acid?
- this is because the test will only work is there is just one type of ion present
- two or more ions means the colors will mix making identification erroneous
bright red?
lithium
golden yellow?
sodium
lilac?
potassium
blue green?
copper (II)
orange red?
calcium
test for positive ions?
- flame tests
and add sodium hydroxide solution: - light blue: copper (II)
- dirty green: iron (II)
- orange- brown: iron (III)
test for sulpahte?
add dilute HCL and add barium chloride, should get a white precipitate
test for carbonate?
add dilute HCL of sizzing and CO2 produced then present
test for ammonium?
add sodium hydroxide solution, and the ammonia gas produced should turn damp red litmus blue
test for water?
- ass anhydrous copper (ii) sulfate and it should go from white to blue
physicals test for water?
- boiling and metling point
test for ammonia gas?
damp red litmus turns blue (heat)
CO2 test?
bubble through lime water
Cl test?
damp blue litmus is bleached
H2 test?
hold lighted splint in mouth of test tube and it should brun with a squeaky pop
