2(h) Chemical tests Flashcards
1
Q
test for group 7 - ions?
A
add dilute nitric acid and silver nitrate:
chlorine: white
bromide: cream
iodide: pale yellow
2
Q
flame test process?
A
- 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
3
Q
why do you clean the wire with a concentrated acid?
A
- 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
4
Q
bright red?
A
lithium
5
Q
golden yellow?
A
sodium
6
Q
lilac?
A
potassium
7
Q
blue green?
A
copper (II)
8
Q
orange red?
A
calcium
9
Q
test for positive ions?
A
- flame tests
and add sodium hydroxide solution: - light blue: copper (II)
- dirty green: iron (II)
- orange- brown: iron (III)
10
Q
test for sulpahte?
A
add dilute HCL and add barium chloride, should get a white precipitate
11
Q
test for carbonate?
A
add dilute HCL of sizzing and CO2 produced then present
12
Q
test for ammonium?
A
add sodium hydroxide solution, and the ammonia gas produced should turn damp red litmus blue
13
Q
test for water?
A
- ass anhydrous copper (ii) sulfate and it should go from white to blue
14
Q
physicals test for water?
A
- boiling and metling point
15
Q
test for ammonia gas?
A
damp red litmus turns blue (heat)