C12 - Testing substances

Question 1

test for hydrogen = positive

Answer 1

lighted splint pops

Question 2

test for o2 = positive

Answer 2

a glowing splint relights

Question 3

test fro co2

Answer 3

turns limewater milky

Question 4

test for chlorine

Answer 4

damp blue litmus paper turns white (bleaches)

Question 5

flame tests process

Answer 5

-nichrome wire loop dipped into concentrated HCL to clean it
-dipped into HCL + metal compound
-hold loop in blue bunsen burner flame
-colour = identifies metal ion

Question 6

flame tests

Answer 6

identifies metal ion by colour of flame

Question 7

mixture of metal ions in flame test

Answer 7

colours can be masked

Question 8

Li+ flame colour

Answer 8

crimson

Question 9

Na+ flame colour

Answer 9

yellow

Question 10

K+ flame colour

Answer 10

lilac

Question 11

flame colour of Ca2+

Answer 11

orange - red

Question 12

Cu2+ flame colour

Answer 12

green

Question 13

Mg2+ flame colour

Answer 13

no colour

Question 14

metal cation test is with

Answer 14

sodium hydroxide

Question 15

metal cation test with sodium hydroxide test

Answer 15

identifies metal positive ions in unknown compound

Question 16

metal cation test with sodium hydroxide for aluminium, calcium, magnesium

Answer 16

white precipitate

Question 17

metal cation test with sodium hydroxide - aluminium

Answer 17

precipitate will dissolve

Question 18

metal cation test with sodium hydroxide test - mg and ca

Answer 18

precipitate will not dissolve
-then can be distinguished with a flame test

Question 19

copper II ions colour precipitate

Answer 19

blue

Question 20

iron II ions colour precipitate

Answer 20

green

Question 21

iron III ions colour precipitate

Answer 21

brown

Question 22

testing for carbonate

Answer 22

fizzing + co2 produced
-when dilute acid is dded

Question 23

group 1 carbonates

Answer 23

soluble whereas most aren’t

Question 24

Halide test

Answer 24

add dilute nitric acid and silver nitrate solution
-if a precipitate forms = present

Question 25

halide test - why add nitric acid

Answer 25

-to dissolve compound and remove carbonate ions
-prevents a precipitate forming with silver ions + carbonate and interfere with the test

Question 26

halide colour precipitate

Answer 26

I = yellow
Cl = white
Br = cream

Question 27

sulfate test

Answer 27

-add dilute HCL and barium chloride solution

Question 28

sulfate test - why add HCL

Answer 28

removes carbonate ions to precipitatae doesn’t form with barium ions

Question 29

sulfate test present

Answer 29

-white precipitate
-this is insoluble barium sulfate

Question 30

modern instrumental pros

Answer 30

-highly accurate
-sensitive
-quicker
-allow small samples to be analysed

Question 31

cons of modern instruments

Answer 31

-expensive
-special training
-only interpreted by comparing to known substances

Question 32

flame emission spectroscopy

Answer 32

-analyse samples for metal ions

Question 33

flame emission spectroscopy process

Answer 33

-sample is heated in a flame
-energy provided excites electrons in metal ions
-allows them o jump to higher energy levels
-when they fall back to lower levels = energy is released as light

Question 34

spectrometer

Answer 34

wavelengths of light produced can be analysed by passing through this

Question 35

spectrometer - metal ions

Answer 35

-each type absorbs/emits its own line spectrum

Question 36

line spectrum

Answer 36

own characteristic pattern of radiation
-identifies metal ions by comparing to a database on a computer

Question 37

spectrometer on concentration

Answer 37

-measures intensity of light with a specific wavelength of a particular metal ion
-machine is calibrated sing known concentrations to give a value

Question 38

spectrometer pros

Answer 38

-provide accurate ways to monitor water for metal ions

Question 39

spectrometer used in

Answer 39

steel industry
-controls trace metals present = quality