m3 - analysis tests

Question 1

testing for carbonate

Answer 1

add dilute acid,
look for effervescence

Question 2

testing for sulfates

Answer 2

dilute HCl (removes carbonate ions)
add BaCl2
a white precipitate forms

Question 3

testing for halides

Answer 3

dilute HNO3 (to remove carbonate ions)
add AgNO3
white ppt: chloride (dissolves in dilute ammonia)
cream ppt: bromide (dissolves in concentrated ammonia)
yellow ppt: iodide (doesn’t dissolve in either)

Question 4

testing for ammonia gas

Answer 4

add NaOH
warm
pungent smell/turns damp red litmus paper blue

Question 5

testing for chlorine gas

Answer 5

turns damp blue litmus paper red, then bleached white

Question 6

adding OH- to test for transition metal ions Cu2+, Fe2+, Fe3+, Mn2+, Cr3+

Answer 6

add OH- ions (NaOH)
look for colour changes

Cu2+ => blue to pale blue ppt
Fe2+ => pale green to dark green ppt
Fe3+ => yellow to orange/brown ppt
Mn2+ => pale pink to pale brown ppt
Cr3+ => violet to dark green ppt