tests

Question 1

explain the flame test

Answer 1

nichrome wire dipped into hcl to clean, hold in roaring flame. dip in hcl again, coat in metal, hold in roaring flame.

Question 2

why does the flame test work

Answer 2

the flame needs to be a roaring flame as it’s colourless. different flames because elements have different electron configurations, electrons temporarily jump to higher level. when they fall back down to original shell, emits energy on the visible spectrum, different electron config has different flames

Question 3

lithium charge + flame

Answer 3

li+, red

Question 4

sodium charge + flame

Answer 4

na+, yellow

Question 5

potassium charge + flame

Answer 5

k+, lilac

Question 6

calcium charge + flame

Answer 6

ca2+, orange-red

Question 7

copper charge + flame

Answer 7

green-blue

Question 8

explain the hydroxide test, plus example

Answer 8

group 1 metal hydroxide + ion -> insoluble metal hydroxide (precipitate) + sulfate
copper sulfate + sodium hydroxide -> copper hydroxide + sodium sulfate

Question 9

explain why hydroxide tests work

Answer 9

g1 metal hydroxides are insoluble in water

Question 10

iron charge + precipitate

Answer 10

fe2, green/ fe3+, orange-brown

Question 11

copper charge + precipitate

Answer 11

cu2+, blue

Question 12

calcium charge + precipitate

Answer 12

ca2+, white

Question 13

zinc charge + precipitate

Answer 13

zn2+, white (dissolves into colourless solution with excess sodium hydroxide)

Question 14

explain sulfate ions test

Answer 14

add dilute hcl to eliminate carbonate + barium chloride to get white precipitate

Question 15

equation for sulfate ions test

Answer 15

Ba2+(aq) + SO4,2-(aq)-> BaSO4(s)

Question 16

explain both carbonate tests

Answer 16

hydrogen ions + carbonate -> carbon dioxide + water
add few drops of hcl. if carbonate present, effervescence will be seen. collect gas, bubble into lime water - the calcium hydroxide will react with the carbon dioxide to make white precipitate (calcium carbonate) turning water cloudy

Question 17

halide ion test

Answer 17

silver fluoride soluble in water. other silver halides are not. to detect halogens add few drops of nitric acid + silver nitrate to get precipitate

Question 18

chloride charge + precipitate

Answer 18

cl-, white

Question 19

bromide charge + precipitate

Answer 19

b-, cream

Question 20

iodide charge + precipitate

Answer 20

i-, yellow