C12 //2

Question 1

How can we test for carbonate ions

Answer 1

add dilute hydrochloric acid to the substance to see if it fizzes, if it does and the gas produced turns limewater cloudy, the substance contains carbonate ions

Question 2

how can we test for halide ions

Answer 2

add dilute nitric acid and then silver nitrate solution

Question 3

what colour precipitate do the halides produce

Answer 3

chlorine - white
bromide - cream
iodide - yellow

Question 4

how can we test for sulfate ions

Answer 4

add dilute hydrochloric acid and then barium chloride solution
if a white precipitate forms, sulfate ions are present

Question 5

give two advantages of instrumental methods of analysis

Answer 5

accurate and very quick

Question 6

give two disadvantages of instrumental methods of analysis

Answer 6

equipment is very expensive and needs specialist training to use

Question 7

what is flame emission spectroscopy

Answer 7

instrumental method that chemists use to analyse samples for metal ions

Question 8

how does flame emission spectroscopy work

Answer 8

the sample is heated in a flame
you analyse the light produced by passing it through a spectroscope
each type of metal ion has its own characteristic pattern
you compare the line spectra with a data base to identify metal ions

Question 9

what is a line spectrum

Answer 9

a metals characteristic pattern for flame emission spectroscopy