12 Experimental techniques and chemical analysis

Question 1

burette advantages and disadvantages

Answer 1

A: quite accurate, very controllable, good for multiple samples
D: hard to clean, not versatile

Question 2

gas syringe advantages and disadvantages

Answer 2

A: precise scale,
D: tendency to develop leaks over time, somewhat expensive

Question 3

solution

Answer 3

one or more solutes dissolved in a solvent

Question 4

saturated solution

Answer 4

solution containing the maximum concentration of a solute dissolved in the solvent at a specified temperature

Question 5

residue

Answer 5

susbtance that remains after evaporation, distilliation, filtration or any similar process

Question 6

filtrate

Answer 6

liquid or solutiont that has passed through a filter

Question 7

acid-base titration apparatus

Answer 7

burette, volumetric pipette, suitable indicator

Question 8

how to find the end-point of a titration using an indicator

Answer 8

colour change

Question 9

paper chromatography

Answer 9

used to separate mixtures of soluble colourless substances, using a suitable solvent and a locating agent

Question 10

Rf

Answer 10

distance travelled by substance/distance travelled by solvent

Question 11

how to test if a subtance is pure

Answer 11

check their melting and/or boiling point

Question 12

testing carbonate

Answer 12

reaction with dilute acid and then testing for carbon dioxide gas (by bubbling through limewater)

Question 13

testing chloride, bromide and iodide

Answer 13

acidifying with dilute nitric acid then adding aqueous silver nitrate:
- Cl- = white ppt
- Br- = cream ppt
- I- = yellow ppt

Question 14

testing nitrate

Answer 14

reduction with aluminium foil and aqueous sodium hydroxide and then testing for ammonia gas

Question 15

sulfate

Answer 15

acidifying with dilute nitric acid and then adding barium nitrate

Question 16

sulfite test

Answer 16

reaction with acidified aqueous potassium manganate

Question 17

testing lithium ion

Answer 17

flame test = crimson flame

Question 18

testing sodium ion

Answer 18

flame test = yellow/orange flame

Question 19

testing potassium ion

Answer 19

flame test - lilac flame

Question 20

testing calcium ion

Answer 20

flame test = brick red flame

Question 21

testing copper ion

Answer 21

Flame test = blue-green flame
NaOH = blue ppt (insoluble in excesss)
NH3 = blue ppt (forms deep blue solution in excess)

Question 22

testing iron (2)

Answer 22

make into a solution and add an excess of NaOH solution or NH3 solution = green precipitate w

Question 23

testing iron (3)

Answer 23

make into a solution and add an excess of NaOH solution or NH3 solution = Brown precipitate

Question 24

testing magnesium ions

Answer 24

Make into a solution and add an excess of NaOH solution or NH3 solution = white precipitate

Question 25

testing aluminium ions

Answer 25

Make into a solution and add an excess of NaOH solution or NH3 solution = white percipitate that dissolve to form a colourless solution with NaOH but the white ppt remains when in excess with NH3

Question 26

testing zinc ions

Answer 26

Make into a solution and add an excess of NaOH solution or NH3 solution = white percipitate, dissolve to form colourless solution with NaOH and NH3