Inorganic Analysis Methods

Question 1

flame test (cation)

Answer 1

the end of a nichrome wire is dipped into HCl (aq) multiple times, then into the solid to be tested and finally placed in a roaring blue flame. The colour of the flame is then noted down.

Question 2

why is a nichrome wire dipped into HCl (aq)?

Answer 2

this removes any impurities so the colours of the flames are clear

Question 3

why use a roaring blue flame?

Answer 3

roaring blue flames have no colour and therefore make the colour of the flame easier to see

Question 4

sodium hydroxide test (cation)

Answer 4

add sodium hydroxide solution (NaOH(aq)) to a solution of the substance to be tested

Question 5

does Mg2+ produce a flame colour?

Answer 5

no, but when magnesium is burned in oxygen, it produces a bright white light

Question 6

how to test for ammonium (NH4+) ions?

Answer 6

sodium hydroxide solution (NaOH) is added to the solid or aqueous substance to be tested and heated. Ammonia gas is produced which turns red litmus paper into blue

Question 7

carbonate/hydrogencarbonate - anion

Answer 7

add any dilute acid to the unknown acid or solution

Question 8

halide ions - anion

Answer 8

To a solution of the unknown add dilute nitric acid, then add silver nitrate solution

Question 9

sulphate test - anions

Answer 9

To a solution of the unknown add dilute hydrochloric acid, then barium chloride solution

Question 10

anion

Answer 10

negative ions - non metals

Question 11

cation

Answer 11

positive ion - metals