Chemical Analysis

Question 1

What colour flame does lithium produce?

Answer 1

Crimson

Question 2

A crimson flame means which element?

Answer 2

lithium

Question 3

A lilac flame means which element?

Answer 3

potassium

Question 4

An orangered / brick red flame means which element?

Answer 4

calcium

Question 5

A yellow flame means which element?

Answer 5

sodium

Question 6

A green flame means which element?

Answer 6

copper

Question 7

what colour flame does potassium produce?

Answer 7

lilac

Question 8

what colour flame does copper produce?

Answer 8

green

Question 9

what colour flame does sodium produce?

Answer 9

yellow

Question 10

what colour flame does calcium produce?

Answer 10

crimson

Question 11

which metals give a white precipitate when a hydroxide is added?

Answer 11

aluminium, calcium and magnesium

Question 12

which metal gives a green precipitate when a hydroxide is added?

Answer 12

iron 2

Question 13

which metal gives a blue precipitate when a hydroxide is added?

Answer 13

copper 2

Question 14

which metal gives a brown precipitate when a hydroxide is added?

Answer 14

iron 3

Question 15

what colour precipitate is produced when hydroxide is added to aluminium?

Answer 15

white

Question 16

what colour precipitate is produced when hydroxide is added to copper 2?

Answer 16

blue

Question 17

what colour precipitate is produced when hydroxide is added to calcium?

Answer 17

white

Question 18

what colour precipitate is produced when hydroxide is added to magnesium?

Answer 18

white

Question 19

what colour precipitate is produced when hydroxide is added to iron 2?

Answer 19

green

Question 20

what colour precipitate is produced when hydroxide is added to iron 3?

Answer 20

brown

Question 21

How do you distinguish between aluminium, calcium and magnesium

Answer 21

AlOH precipitate dissolves to form a colourless solution when more NaOH is added
MgOH and CaOH remain unchanged

Question 22

How do you test for a carbonate ion?

Answer 22

acid (usually dilute HCl but any works) added to test compound
CO2 bubbles
limewater test

Question 23

how do you test for copper?

Answer 23

green flame
blue precipitate when hydroxide added

Question 24

how do you test for calcium?

Answer 24

crimson flame
white precipitate when hydroxide added

Question 25

how do you test for aluminium?

Answer 25

white precipitate when hydroxide added. when more is added it dissolves to form a colourless solution

Question 26

how do you test for iron 2?

Answer 26

green precipitate when hydroxide added

Question 27

how do you test for iron 3?

Answer 27

brown precipitate when hydroxide added

Question 28

how do you test for sulfate ions?

Answer 28

barium ions react with sulfate ions to form white precipitate: add a few drops of dilute HCL add a few drops of dilute BaCl

Question 29

how do you test for halide ions?

Answer 29

add silver nitrate

Question 30

which halide ion produces white ppt when silver is added?

Answer 30

chloride

Question 31

which halide ion produces cream ppt when bromide is added?

Answer 31

bromide

Question 32

which halide ion produces yellow ppt when silver is added?

Answer 32

iodide

Question 33

what colour ppt is produced when silver nitrate is added to bromide?

Answer 33

cream

Question 34

what colour ppt is produced when silver nitrate is added to iodide?

Answer 34

yellow

Question 35

what colour ppt is produced when silver nitrate is added to chloride?

Answer 35

white

Question 36

what are the problems with simple tests?

Answer 36

not very sensitive subjective-> false positives can't cope w/ mixtures not quantitative slow, one at a time

Question 37

give an example of an instrumental method for chemical analysis

Answer 37

flame emission spectroscopy- uses a prism to split wavelengths from a flame each element has a unique series of wavelengths

Question 38

what are the advantages of instrumental methods?

Answer 38

can do dilute solutions and mixtures objective; is there or not v. sensitive quantitative can be automated

Question 39

disadvantages of instrumental methods?

Answer 39

expensieve, needs calibration, needs training