chemical analysis

Question 1

calcium (Ca2+) flame test result

Answer 1

orange-red flame

Question 2

copper (Cu2+) flame test result

Answer 2

green flame

Question 3

sodium (Na+) flame test result

Answer 3

yellow/orange

Question 4

potassium (K+) flame test result

Answer 4

lilac flame

Question 5

lithium (Li+) flame test result

Answer 5

crimson flame

Question 6

what do group 3 metal ions do when reacted with sodium hydroxide

Answer 6

form a white precipitate that redissolves in excess sodium hydroxide

Question 7

what colour precipitate do group 1 and 2 metal ions form when reacted with sodium hydroxide

Answer 7

white precipitate

Question 8

what colour precipitate does iron (II) form?

Answer 8

green precipitate

Question 9

what colour precipitate does iron (III) form?

Answer 9

brown precipitate

Question 10

what colour precipitate does copper (II) form?

Answer 10

blue precipitate

Question 11

what are the products of reactions between a carbonate and a dilute acid

Answer 11

a salt
water
carbon dioxide

Question 12

how do you test for halide ions?

Answer 12

add dilute nitric acid
then add silver nitrate

Question 13

what halide ion forms a yellow precipitate

Answer 13

iodide

Question 14

what halide ion forms a white precipitate

Answer 14

chloride ions

Question 15

what colour precipitate does bromide ions form?

Answer 15

cream

Question 16

what is the method for testing for sulfate ions?

Answer 16

acidify with dilute hydrochloric acid
add barium chloride

Question 17

what forms if sulfate ions are present?

Answer 17

a white precipitate

Question 18

why do we add nitric acid when testing for halides?

Answer 18

the nitric acid removes any carbonates,
stopping a precipitate forming with the silver added after

Question 19

what are the advantages and disadvantages of using instrumental methods in chemical analysis?

Answer 19

advantages:
greater sensitivity and accuracy
faster results
able to analyse smaller/ tiny samples

disadvantages:
instruments are often expensive
special training is required to operate the instruments
results are often only useful when compared to a known substance

Question 20

what is the method for flame emission spectroscopy? (2steps)

Answer 20

1)place a sample of the metal in a flame, light will be given off
2) light given off is captured by a spectroscope, the spectroscope produces a line spectrum by differentiating the different wavelengths

Question 21

what is the output of a spectroscope?

Answer 21

a line spectra

Question 22

what can we use flame emission spectroscopy to investigate?

Answer 22

what metal ions are present
what concentrations the ions are in

Question 23

what do impurities do to the boiling point of a substance?

Answer 23

increase the boiling point and increase the range at which the substance boils